| Paper | Title | Page |
|---|---|---|
| TUPCH003 | Diagnostics and Timing at the Australian Synchrotron | 995 |
|
||
| The 3GeV Australian Synchrotron will begin operation in March 2007. This paper outlines the storage ring diagnostics systems and the injection timing system. The diagnostics system includes an optical beamline with streak camera, an x-ray beamline with pinhole array, a diagnostic straight with fast feedback kicker, stripline, direct current current transformer, and a four-fingered scraper. Over the 14 sectors there are 98 beam position monitors and 14 movable beam loss monitors. The timing system is based on a static injection system with the storage ring bucket to be filled targeted by delaying the firing of the electron gun. | ||
| TUPCH004 | Commissioning of the LNLS X-ray BPMs | 998 |
|
||
| We present experimental results of the commissioning of staggered-pair blade X-Ray beam position monitor (XBPM) recently developed and installed at the diagnostic beamline of the UVX electron storage ring at the Brazilian Synchrotron Light Laboratory (LNLS). The results obtained with a prototype XBPM indicate that the short-term and long-term data are both in agreement with the data from a commercially acquired XBPM installed at the same beamline, as well as with the data of the electron storage ring RF BPMs. In this paper we present the commissioning results of the LNLS XBPM. | ||
| TUPCH006 | A Wideband Intercepting Probe for the TRIUMF Cyclotron | 1001 |
|
||
| An intercepting probe for the TRIUMF cyclotron capable of measuring the phase and time structure of the circulating beam was designed, manufactured, installed into the tank and tested. A model of the probe head in the form of a 50 Ohm parallel plate transmission line was developed and simulated to operate up to 2 GHz. Thermal simulations show that the probe can withstand at least 500 nA of average current for the 500 MeV beam. In laboratory tests the probe demonstrated a bandwidth in excess of 1 GHz. The probe was mounted on a 3 m long drive and is capable of travelling over 0.5 m at an angle of 27 degree w.r.t. the cyclotron radius. The signals extracted from the probe are processed by a pair of diplexers, where low frequency and high frequency components are separated. The low frequency signal is directed to our standard electronics for processing and provides both dc current and a time of flight signal with a rise time of about 100 ns. At the high frequency output a signal-to-noise ratio of about 4 at 250 nA average current and 0.1 % duty cycle was measured in the presence of rf background from the cyclotron resonators. A bunch time structure as short as 1 ns was resolved. | ||
| TUPCH007 | High Resolution BPM for the Linear Colliders | 1004 |
|
||
| The beam-based alignment and feedback systems which are essential for the operation of the future colliders use some high resolution Beam Position Monitors (BPM). In the framework of CARE/SRF, the task of CEA/DSM/DAPNIA (Saclay) is the design, the fabrication and the beam test of a BPM in collaboration with DESY. This system is composed of a RF re-entrant cavity with a beam pipe radius of 78mm and an analog electronics having several signal processing steps to reject the monopole mode. Thanks to its high position resolution (better than 1μm) and its high time-resolution (around 10ns), it is a candidate for the X-FEL at DESY and the ILC. Indeed the chosen coupling allows the bunch to bunch measurement and the separation between the monopole and dipole modes. Moreover, this BPM is designed to be used in a clean environment, at the cryogenic and room temperatures. | ||
| TUPCH008 | Behavior of the BPM System During the First Weeks of SOLEIL Commissioning | 1007 |
|
||
| SOLEIL, a new synchrotron light source built near Paris in France, is pioneering a new high resolution electron Beam Position Monitor (BPM) system to achieve stability of the beams at the micron level, as required for the beamlines. The same BPM system allows also measurement of the beam position in turn-by-turn mode for various machine physics studies. The system combines the high stability characteristic of multiplexed input channels and the flexibility of a digital system. Instrumentation Technologies developed the Libera module upon SOLEIL proposals and requirements. The performances of the system evaluated after the Booster and the storage ring commissioning will be presented. | ||
| TUPCH009 | Beam Measurements and Manipulation of the Electron Beam in the BESSY-II Transferline for Topping Up Studies | 1010 |
|
||
| The BESSY-II storage ring based synchrotron radiation source will be upgraded to allow for continuous topping up operation. In order to achieve a high injection efficiency between the booster synchrotron and the storage ring, the transferline will be equipped with novel beam size monitors and collimators. This paper describes the collimator design and first beam measurements of the transverse emittance. The transverse emittance is measured using the quadrupole scan technique. The data taking and the analysis procedure is given together with results and comparision with simulations. | ||
| TUPCH010 | Profile Measurement by Beam Induced Fluorescence for 60 MeV/u to 750 MeV/u Heavy Ion Beams | 1013 |
|
||
| At the planned heavy ion facility FAIR very intense beams of heavy ions will be transported between various synchrotrons and focused on targets for secondary ion productions. For the transverse profile determination only non-destructive methods are suited due to the large deposed beam power. We investigated experimentally the Beam Induced Fluorescence (BIF) method. Due to the atomic collision by the beam ions the residual gas N2 is excited to fluorescence levels. Single photon detection is performed by a double MCP image intensifier coupled to a digital CCD camera. Extensive experimental studies (with the today available lower ion currents) were performed to determine the photon yield and the background contribution for different ion species and beam energies. The measured profiles show a good correspondence to other methods as long as the vacuum pressure by a regulated N2 inlet is below 10-1 mbar. Based on the experimental results, the layout for a BIF profile determination will be discussed. | ||
| TUPCH011 | Innovative Beam Diagnostics for the Challenging FAIR Project | 1016 |
|
||
| The planned FAIR facility consists of two heavy ion synchrotrons and four large storage rings. The super-conducting synchrotrons are build for high current operation and secondary ion production. A large variety of low current secondary beams is stored and cooled in the four storage rings. A complex operation scheme with multiple use of transport lines is foreseen. This demands an exceptional high dynamic range for the beam instrumentation. Due to the enormous beam power, non-destructive methods are mandatory for high currents. For the low current secondary beams, non-destructive diagnostics are also preferred due to the low repetition rate. Precise measurements of all beam parameters and automatic steering or feedback capabilities are required due to the necessary exploitation of the full ring acceptances. Moreover, online beam-corrections with short response times are mandatory for the fast ramping super-conducting magnets. Due to the ultra-high vacuum condition and the demanding measurement accuracy, novel technical solution are foreseen. An overview of the challenges and projected innovative solutions for various diagnostic installations will be given. | ||
| TUPCH012 | Digital Techniques in BPM Measurements at GSI-ISI | 1019 |
|
||
| In this paper we describe new approaches for BPM measurements in hadron accelerators, which have strongly varying beam parameters such as intensity, accelerating frequency and bunch length. Following signal dynamic adjustment, direct digitalization and treatment of digitized data, we should reach a BPM resolution of 0.1mm. Interchangeability of this method between accelerators should be provided, which results in autonomous data treatment algorithms, free of external status and timing signalling. This should ensure the usability of the system in other bunched accelerator rings. Different operation modes are intended for allowing online storage of beam position data over full acceleration cycles as well as storage of beam waveforms in regions of acceleration that are of special interest e.g. transition, kicking, bunch gymnastics. First results of realised hardware/software combinations will be introduced and discussed. | ||
| TUPCH013 | Numerical Calculations of Position Sensitivity for Linear-cut Beam Position Monitors | 1022 |
|
||
| In this contribution the results of simulations performed for different geometries of linear-cut Beam Position Monitors (BPMs) are compared for two design types: i)based on metal electrodes and ii)using a metal coated ceramics. The advantage of the ceramic solution is a compact construction allowing easy positioning. Contrary, the construction based on the metal electrodes benefits from its simplicity. The main goals in optimization are the sensitivity and linearity of the position determination. High position sensitivity can be achieved by the reduction of the plate-to-plate cross talks caused by coupling capacities. For instance, the insertion of an additional guard ring into the gap between the active plates leads to an increase of the sensitivity by about 30%. This insertion is necessary in case of ceramic solution: The large ceramics permeability enlarges the coupling capacity by about a factor of four. The careful geometrical arrangement allows to avoid resonances in the interesting frequency range i.e. from 0.2 to 200MHz. The displayed simulations are performed using CST Microwave Studio. The investigated BPMs will be used in the FAIR facility presently under design at GSI. | ||
| TUPCH014 | Machine Protection by Active Current-transmission Control at GSI-UNILAC | 1025 |
|
||
|
Toroidal beam current transformers (BCT) are installed at dedicated locations along the UNILAC accelerator. They provide an output signal with a fixed transimpedance. Dedicated signal pairs from consecutive transformers drive differential integrator stations. If preset protection levels are exceeded due to beam charge loss during the macro-pulse, fast interlock signals are generated. The actual beam pulse is instantaneously truncated by a fast beam chopper, avoiding any thermal damage or radio-activation of machine components. A new BCT macro-pulse selector/display is presently under construction, which will provide time structure observation of multiple UNILAC macro-pulses, as well as long-term data logging. The hardware is set up with PXI components from National Instruments, running a multi-client/server controller software under LabViewRT®. Offline-analysis of the accumulated BCT data is expected to improve the protection system's operation and reliability. An overview of the system layouts, technical details, and relevant operational results will be presented. |
||
| TUPCH015 | Integrated Beam Diagnostics Systems for HICAT and CNAO | 1028 |
|
||
| An integrated system for beam diagnostics was produced at GSI for the heavy-ion cancer treatment facility HICAT of the Heidelberg university clinics. A set of 92 manifold beam diagnostic devices allows automated measurements of the main beam parameters such as beam current, profile or energy. The beam diagnostic subsystem is completely integrated in the overall accelerator control system and its timing scheme. This paper reports on the underlying design patterns for the abstraction of the beam diagnostic devices towards the control system. Event-counting devices, i.e. scintillating counters and ionization chambers, are presented as examples of the diagnostic devices in the synchrotron and high-energy beam transport section of HICAT. Additionally, it is shown that the well-defined building blocks of the beam instrumentation made it possible to prepare almost identical devices including the manual control software, to be used in the CNAO facility (Centro Nazionale di Adroterapia Oncologica) presently under construction in Pavia, Italy. | ||
| TUPCH016 | Numerical Simulation of Synchrotron Radiation for Bunch Diagnostics | 1031 |
|
||
| For the operation of the VUV-FEL at DESY, Hamburg, the longitudinal charge distribution of the electron bunches that drive the free electron laser is of high importance. One novel method to measure the bunch shape is to analyze the coherent far-infrared synchrotron radiation generated at the last dipole magnet of the first bunch compressor. For the correct interpretation of the results it is mandatory to know how various parameters, like the bunch shape and path, the vacuum chamber walls, the optical beamline, etc., influence the observed spectrum. The aim of this work is to calculate the generation of synchrotron radiation inside the bunch compressor with the emphasis of including the effects of the vertical and horizontal vacuum chamber walls in the vicinity of the last dipole magnet. Challenging problems for the numerical simulations are the very short wavelength and the broad frequency range of interest. As a first step, it is shown how the radiation leaving the vacuum chamber, that is generated by a single point charge, can be calculated with the help of the uniform theory of diffraction (UTD). | ||
| TUPCH018 | Fast Beam Dynamics Investigation Based on an ADC Filling Pattern Measurement | 1034 |
|
||
| A diagnostic tool to determine the longitudinal particle filling pattern has been installed at the 1.5 GeV electron storage ring DELTA. The instrument is PC-based using an ADC-conversion at a sampling rate of 2 GS/s and a nominal bandwidth of 1 GHz which is applied to the sumsignal of a single storage ring beam position monitor. By sampling over successive turns the resolution is enhanced by one order of magnitude allowing an easy access to the longitudinal particle distribution inside the ring. The data obtained turn-by-turn over hundreds of revolutions can be further analysed by FFT-techniques allowing a very fast detection (~ 1 s) of longitudinal coupled bunch mode (CBM) instabilities from the phase modulated spectrum. The application of the FFT to the amplitude modulated particle distribution moreover allows a "post mortem"-investigation of CBM induced beam loss. The paper will present the layout of the diagnostic system and will report on filling pattern measurements as well as on investigations of longitudinal CBM-instabilities. | ||
| TUPCH019 | Laser-based Beam Diagnostic for the Front End Test Stand (FETS) at RAL | 1037 |
|
||
| High power proton accelerators (HPPA) are required for several future projects like spallation sources or a neutrino factory. Compared with existing machines the beam power therefore has to be increased by a factor of 30. The Front end test stand at RAL is being built to demonstrate that a chopped Hminus beam of 60 mA at 3 MeV with 50 pps and sufficiently high beam quality, as required for all proposed Proton drivers, can be built. For the test stand a comprehensive set of beam diagnostics is also required. Due to the high beam energy and power non destructive diagnostic methods are favorable. Hminus beams offer the possibility to use intense laser light to detach the additional electron and use the produced particles for beam diagnostics. The principle is appropriate to determine the transversal beam density distribution as well as the transversal and longitudinal beam emittance in front and behind the RFQ. A detailed layout of the beam diagnostics including a discussion of the predicted spatial and temporal resolution and the dynamic range of the proposed devices will be presented. | ||
| TUPCH021 | Principles of longitudinal beam diagnostics with coherent radiation | 1040 |
|
||
| The Kramers-Kronig dispersion relation connects the real and imaginary part of a response function under very general assumptions. It is used in the context of accelerator physics for longitudinal bunch diagnostics as a phase retrieval technique: the modulus of the complex form factor (the Fourier transform of the charge distribution) is accessible experimentally, and the missing phase then (partially) reconstructed to allow an inversion of the Fourier transform. Contrary to real and imaginary part, the connection between modulus and phase is not unique anymore due to the possibility of zeros of the form factor in the complex frequency plane that cannot be measured. This paper gives a mathematically explicit, step-by-step derivation of the phase reconstruction technique for bunch diagnostics, and it explains the problem of zeros and their practical effect with some examples. The intention is not utmost mathematical rigour, but a clear, accessible explanation of all steps involved. | ||
| TUPCH022 | Large Horizontal Aperture BPM for use in Dispersive Sections of Magnetic Chicanes | 1043 |
|
||
| A beam position monitor with a large horizontal aperture for use in dispersive sections of FLASH magnetic chicanes will be installed in October 2006. It has a horizontal range of 13 cm and a resolution requirement of better than 10 microns. A stripline design mounted perpendicularly to the the electron beam direction is used to provide broadband electrical pulses traveling in opposite directions, the phases of which give a measure of the beam position. The phase measurement will be accomplished through an optical method developed for a beam arrival time monitor. Results from simulation and recent beam arrival-time measurements will be used to justify expectations for the BPM performance. | ||
| TUPCH023 | Direct Observation of Beam-beam Induced Dynamical Beta Beating at HERA | 1046 |
|
||
| The Hadron Electron Ring Anlage (HERA) at DESY provides collisions between a 920 GeV proton beam and a 27.5 GeV electron beam in two interaction regions. The strong beam-beam force, which mainly affects the electrons, induces a tune shift together with a dynamical beta beat. The latter leads to a modification of the transverse beam profile, which can be observed in different profile monitors in HERA. The time-like evolution of the electron beam shape during luminosity tuning and before and after dump of the proton beam, averaged over all bunches, could be studied by means of a synchrotron radiation profile monitor. Measurements with a wire scanner allowed to see the beam-beam force's influence on each individual bunch at the expense of resolution. The observations could be explained qualitatively in the frame of linear incoherent beam-beam interaction. | ||
| TUPCH024 | Comparative Study of Bunch Length and Arrival Time Measurements at FLASH | 1049 |
|
||
| Diagnostic devices to precisely measure the longitudinal electron beam profile and the bunch arrival time require elaborate new instrumentation techniques. At the VUV-FEL, two entirely different methods are used. The bunch profile can be determined with high precision by a transverse deflecting RF structure. The method is disruptive and does not allow to monitor multiple bunches in a macro-pulse train. Therefore, it is augmented by two non-disruptive electro-optical devices, called EO and TEO. The EO setup uses a dedicated diagnostic laser synchronized to the machine RF. The longitudinal electron beam profile is encoded in the intensity profile of a chirped laser pulse and analyzed by looking at the spectral composition of the pulse. The second setup, TEO, utilizes the TiSa-based laser system used for pump-probe experiments. Here, the temporal electron shape is encoded into a spatial dimension of laser pulse by an intersection angle between the laser and the electron beam at the EO-crystal. In this paper, we present a comparative study of bunch length and arrival time measurements performed simultaneously with all three experimental techniques. | ||
| TUPCH025 | Precision RF Gun Phase Monitor System for the VUV-FEL | 1052 |
|
||
| For RF photo-injectors, the properties of the high brightness beam critically depend on the synchronization between the RF gun acceleration phase and the photo-cathode laser. At the VUV-FEL, the phase stability is determined by operating the RF gun close to zero-crossing RF phase. This allows the conversion of phase variations into charge variations which then is readout by a precision charge measurement system based on toroids. In this paper, we discuss the limitation of this method. Resolution reduction of the charge measurement system due to electro-magnetic-interference is discussed in detail. | ||
| TUPCH026 | Single Shot Longitudinal Bunch Profile Measurements at FLASH using Electro-optic Techniques | 1055 |
|
||
| For the high-gain operation of a SASE FEL, extremly short electron bunches are essential to generate sufficiently high peak currents. At the superconducting linac of the VUV-FEL at DESY, we have installed an electro-optic experiment with temporal decoding and spectral decoding to probe the time structure of the electric field of single sub 200fs e-bunches. In this technique, the field-induced birefringence in an electro-optic crystal is encoded on a chirped ps laser pulse. The longitudinal electric field profile of the electron bunch is then obtained from the encoded optical pulse by a single-shot cross correlation with a 30 fs laser pulse using a second-harmonic crystal (temporal decoding) or by a single-shot measurement of its spectrum (spectral decoding). In the temporal decoding measurements an electro-optic signal of 230fs FWHM was observed, and is limited by the material properties of the particular electro-optic crystal used. Bunch profile and time jitter measurements were obtained simultaneously with VUV SASE operation. | ||
| TUPCH027 | Time Resolved Single-shot Measurements of Transition Radiation at the THz Beamline of FLASH using Electro-optic Spectral Decoding | 1058 |
|
||
| Single-shot electro-optic detection was used to measure the temporal profile of coherent transition radiation (CTR) pulses at the VUV-FEL at DESY. The CTR was generated from single bunches kicked to an off-axis screen, with the radiation transported through a 20m long transfer line imaging the CTR from a radiation screen to an experimental station outside the accelerator tunnel. Bipolar pulses with a FWHM less than 1ps have been measured and are consistent with simulations of the propagation of radiation through the transfer line. | ||
| TUPCH028 | Layout of the Optical Synchronization System for FLASH | 1061 |
|
||
| The present RF synchronization system of the VUV-FEL can typically stabilize the arrival time of the electron bunches at the undulator to about 200 fs on a timescale of minutes and to several picoseconds on a timescale of hours. To improve the machine stability and to ensure optimal performance for the VUV-FEL user facility, a new ultra-precise timing system is mandatory. The optical synchronization system under construction will satisfy three goals: Firstly, it provides a local oscillator frequency with the same stability as the existing low-level RF regulation, secondly, it can synchronize the experimental lasers of the FEL users with a precision in the order of 30 fs, thirdly, it provides an ultra-stable reference for beam arrival time measurements and enables a feedback on the electron beam to compensate residual drifts and timing jitter. The optical synchronization system is based on an optical pulse train from a mode-locked laser with a highly stabilized repetition rate. This paper describes the proposed layout of the optical synchronization system, the integration into the machine layout and the diagnostic experiments to monitor the performance of the system. | ||
| TUPCH029 | High-precision Laser Master Oscillators for Optical Timing Distribution Systems in Future Light Sources | 1064 |
|
||
| X-ray pulses with a pulse duration in the 10 fs regime or even less are needed for numerous experiments planned at next generation free electron lasers. A synchronization of probe laser pulses to the x-ray pulses with a stability on the order of the pulse width is highly desirable for these experiments. This requirement can be fulfilled by distributing an ultra-stable timing signal to various subsystems of the machine and to the experimental area to provide synchronization at the fs level over distances of several kilometers. Mode-locked fiber lasers serve as laser master oscillators (LMO), generating the frequencies required in the machine. The pulse train is distributed through length-stabilized fiber links. This paper focuses on the LMO, devoting special attention to the phase noise properties of the frequencies to be generated, its reliability to operate in an accelerator environment, and the residual timing jitter and drifts of the RF feedback for the fiber links. A prototype experimental system has been constructed and tested in an accelerator environment and its performance characteristics will be evaluated. | ||
| TUPCH030 | A Beam Diagnostics System for the Heidelberg Cryogenic Storage Ring CSR | 1067 |
|
||
| The storage of rotationally non-excited molecules and highly charged ions requires lowest temperatures and vacuum pressures. At the MPI-K Heidelberg a cryogenic storage ring (CSR) for atomic and molecular physics experiments is under development. The CSR shall allow operation at temperatures of 2 K and pressures down to 1·10-15 mbar. The ring consists of electrostatic elements and has a circumference of ~35 m. It is housed inside a large cryostat, cooled by a (20W @ 2K) Helium refrigerator. To reach low UHV pressures already at room temperature the whole machine has to be bakeable up to 300°C. These boundary conditions, together with the low charge states, low velocities and low intensities (1nA-1muA) of the ions, put strong demands on the beam diagnostics system. Some beam parameters like profile, position and intensity cannot be measured with “standard” beam diagnostics technology. Here new or further developments are required. The paper gives a general view of the beam diagnostics concept for the CSR and shows in more detail possible solutions for measurement of beam position and beam profile. | ||
| TUPCH031 | A New SQUID-based Measurement Tool for Characterization of Superconducting RF Cavities | 1070 |
|
||
| In this contribution a LTS-SQUID based measurement tool for characterization of superconducting RF cavities for the upcoming X-FEL project at DESY will be presented. The device makes use of the Cryogenic Current Comparator (CCC) principle and measures the so-called dark current, generated e.g. by superconducting cavities at high voltage gradients. To achieve the maximum possible energy the gradients should be pushed near to the physical limit of 50 MV/m. The measurement of the undesired field emission of electrons (the so-called dark current) in correlation with the gradient will give a proper value to characterize the performance of the RF cavities. The CCC mainly consists of a high performance LTS-DC SQUID system which is able to measure extremely low magnetic fields, e.g. caused by the extracted dark current of the RF cavities. Therefore, a special designed toroidal niobium pick-up coil for the passing electron beam is superconducting connected across the input coil of the SQUID. The noise limited sensitivity of the CCC as well as new experimental results with the whole measurement device assembled in a special wide-necked LHe cryostat will be presented. | ||
| TUPCH032 | Precise Measurements of the Vertical Beam Size in the ANKA Storage Ring with an In-air X-ray Detector | 1073 |
|
||
| A major part of the X-rays generated in the ANKA dipole magnets is unused by the experimental beamlines and is, on a number of dipoles, absorbed in a conical shaped Copper absorber. The 8 mm thickness that it presents lets a tiny fraction of the hard X-rays above 70KeV enter the free air space behind it. The transmitted power of only a few uW/mrad hor. is sufficient to be detected, with sub-second measurement time, by a novel In-Air X-ray detector. This extremely compact and low-cost device is situated just behind the absorber. The design, developed and in use at the ESRF, is based on a Cadmium Tungstenate (CdWO4) scintillator converting X-rays into visible light that is collected and focused onto a commercial CCD camera. Since the small vertical divergence of the high energy photons and the distance of the detector from the source point are known, it is possible to derive the vertical electron beam size with a high intrinsic precision. This paper presents results of beam size measurements as a function of various ANKA machine parameters, that illustrates the great diagnostic potential of this type of detector for a 2.5GeV medium energy light source like ANKA. | ||
| TUPCH033 | Automated Beam Optimisation and Diagnostics at MAMI | 1076 |
|
||
|
At the Institut fur Kernphysik (IKPH) of Mainz University the fourth stage of the Mainz Microtron (MAMI), a 855MeV to 1500MeV Harmonic Double Sided Microtron (HDSM), is now on the verge of first operation*. To provide an automated beam optimisation, low-Q-TM010 and TM110 resonators at each linac of the three cascaded RTMs and the two linacs of the new HDSM are used. These monitors deliver position, phase and intensity signals of each recirculation turn when modulating the beam intensity with 12ns-pulses (diagnostic pulses, max. rep. rate 10kHz). For operating the HDSM an extended system for displaying and digitising these signals was developed. High-bandwidth ADCs allow very comfortable to analyse, calibrate and automatically optimise the beam positions and phases during operation. The system is also used to adjust the transversal and longitudinal focussing according to the design parameters. Synchrotron radiation monitors, providing beam sizes and positions out of the bending magnets for each turn and on the entrance and exit of the linac axis, were a very helpful tool for beam-matching between the RTMs. Therefore a similar system was planned and constructed for the HDSM.
*A. Jankowiak et al. “Status Report on the Harmonics Double Sided Microtron of MAMI C”, this conference. |
||
| TUPCH035 | Fine Spatial Beam Loss Monitoring for the ISIS Proton Synchrotron | 1079 |
|
||
| Beam loss detection at the ISIS synchrotron is achieved using a series of 3 and 4 metre long argon gas ionisation tubes placed around the inside track of the main ring and along the injector and extraction sections. Even with this level of diagnostics problems have occurred, for example, inside a main dipole within the accelerator ring where small concentrated areas of loss have resulted in severe damage to the RF shield. This type of loss cannot be easily resolved using the conventional argon gas system due to the length of the detectors and their distance from the vacuum vessel (around 2m). We report here the development of a compact beam loss monoitoring system which has been installed inside a dipole between the vacuum vessel and the main body of the dipole. The system comprises of six 150 sq. cm. (BC408) plastic scintillators connected to photo-multiplier tubes via fibre optic bundles. Measurements taken demonstrate that the new system can easily resolve complex beam loss patterns along the dipole while remaining robust to the high radiation environment. We also report here details of our PXI based data collection and display system. | ||
| TUPCH036 | Modelling of Diagnostics for Space Charge Studies on the ISIS Synchrotron | 1082 |
|
||
| The ISIS Facility at the Rutherford Appleton Laboratory in the UK produces intense neutron and muon beams for condensed matter research. It is based on a 50 Hz proton synchrotron which, once the commissioning of a new dual harmonic RF system is complete, will accelerate about 3.5·1013 protons per pulse from 70 to 800 MeV, corresponding to mean beam powers of 0.2 MW. Transverse space charge is a key issue for both present and proposed upgrades to the machine, and is the focus of current R&D studies. Experiments on the ISIS ring are central to this work, therefore understanding and quantifying limitations in present and proposed diagnostics is essential. This paper presents work studying and modelling the ISIS residual gas profile monitors, including the effects of non-uniformity in sweep fields, space charge and images. Progress on related work looking at other important diagnostics, e.g., position and envelope monitoring, will also be summarised. | ||
| TUPCH037 | Development of Emittance Scanner Software for ISIS | 1085 |
|
||
| Horizontal and vertical Faraday cup and slit scanners are used on ISIS, the 800MeV pulsed neutron source at the Rutherford Appleton Laboratory, to calculate the emittance of the beam. Software has been written in C++ to control the scanners, acquire and display beam data and compute an emittance value for the beam. The software allows the user more control, and has the ability to scan over a wider range, than was previously available. | ||
| TUPCH038 | Beam Loss Monitoring and Machine Protection Designs for the Daresbury Laboratory Energy Recovery Linac Prototype | 1088 |
|
||
| Daresbury Laboratory is currently constructing an energy recovery linac prototype (ERLP). This is to carry out the necessary research and development of the technology of photo-cathode electron guns and superconducting linacs so that a fourth generation light source (4GLS) can be designed and constructed. Beam loss monitoring and machine protection systems are vital areas for the successful operation of the ERLP. These systems are required, both for efficient commissioning and for hardware protection during operation. This paper gives an overview of the system requirements, options available and details of the final design specification. | ||
| TUPCH039 | A Phase Space Tomography Diagnostic for Pitz | 1091 |
|
||
| The Photo Injector Test Facility at DESY in Zeuthen (PITZ) is a European collaboration developing RF photocathode electron guns for light source and linear collider projects. As part of the collaborative work being partially funded by the EU's FP6 programme, CCLRC Daresbury Laboratory and DESY are designing and building a phase space tomography diagnostic based on a set of multiple quadrupoles and view screens. In order to measure the beam emittance, four screens with intermediate quadrupole doublets will be used. The equipment will be installed and tested at PITZ as part of the facility upgrade presently ongoing. Following simulations of the gun using the ASTRA code at a range of energies, simulations of the electron beam parameters through the matching and tomography sections must be undertaken in order to specify the optimum arrangement of magnets and screens. | ||
| TUPCH041 | Electro-optic Diagnostics on the Daresbury Energy Recovery Linac | 1094 |
|
||
| An electro-optic longitudinal bunch profile monitor is being implemented on the 4GLS prototype energy recovery linac (ERL/p) at Daresbury Laboratories and will be used both to characterise the electron bunch and to provide a testbed for electro-optic techniques. The electro-optic station is located immediately after the bunch compressor, and within the FEL cavity; its location allows it to draw on nearby beam profile monitors and CTR and CSR diagnostics for calibration and benchmarking. We discuss the implementation and planned studies on electro-optic diagnostics with this diagnostic station. | ||
| TUPCH042 | The Optical System for a Smith-Purcell Experiment at 45MeV | 1097 |
|
||
| Smith-Purcell (SP) radiation has been used to investigate the longitudinal profile of a 45MeV, picosecond long bunched beam at the FELIX facility, FOM Institute. The three important optical elements that made this experiment possible were (i) high quality optical filters, (ii) nonimaging light concentrators, (iii) and a system to rapidly change between gratings. | ||
| TUPCH043 | Observations of the Longitudinal Electron Bunch Profile at 45MeV Using coherent Smith-Purcell radiation | 1100 |
|
||
| Coherent Smith-Purcell (SP) radiation has been used to determine the longitudinal profile of the electron bunch at the FELIX facility, FOM Institute. Far-infrared radiation was detected using a simple, compact arrangement of 11 pyroelectric detectors. Background radiation was suppressed through the use of high quality optical filters, and an efficient light collection system. The measured bunch profile was most closely in agreement with 90% of the particles contained within 5.5ps, with an approximately triangular temporal profile. | ||
| TUPCH044 | Turn-by-turn Data Acquisition and Post-processing for the Diamond Booster and Storage Ring | 1103 |
|
||
| The Diamond booster and storage ring are equipped with Libera Electron Beam Position Processors with turn-by-turn capabilities. We describe here the turn-by-turn data acquisition system and the software used for post-processing the beam data. The signals from the Libera boxes are acquired and controlled with EPICS and then transferred to the MATLAB environment via the MATLAB Channel Access. Here they are post-processed using MATLAB capabilities and dedicated software linked to MATLAB. Examples of data acquired and measurements performed during Diamond booster and storage ring commissioning are reported. | ||
| TUPCH045 | First Use of Current and Charge Measurement Systems in the Commissioning of Diamond | 1106 |
|
||
| This paper will discuss the results obtained from the charge and current measurement systems installed in Diamond during the commissioning stage of operation. The charge measurements are gathered from integrating current transformers and Faraday cups, while the current is measured using a DC current transformer in each ring. The measured beam parameters will be investigated, as well as how well the devices performed against expectations. | ||
| TUPCH046 | Performance of Global Diagnostics Systems during the Commissioning of Diamond | 1109 |
|
||
| This paper summarises data acquired with beam diagnostics systems distributed globally through Diamond's Linac, transfer paths, booster and storage ring. It shows results from the electron beam position monitors using their capabilities to monitor transient events, the booster ramp as well as stored beam. The performance derived from real beam measurements is compared to measurements obtained in the lab using signal and pulse generators. Other systems of widespread use are screens and synchrotron light monitors. Their performance and control system integration based on IEEE1394 camera technology is presented. Finally, first results from the fast and slow beam loss monitoring systems are described. | ||
| TUPCH047 | Diamond Optical Diagnostics: First Streak Camera Measurements | 1112 |
|
||
| We present in this paper a first set of measurements of the six-dimensional phase-space of the electron beam in the Diamond storage ring. We recall the predicted performance and compare it with our first measurements. The two pinhole cameras measure the beam size, from which we retrieve the energy spread and the emittance of the beam in both horizontal and vertical directions. We have designed a robust and simple UV-visible beamline, to measure the electron bunch profile and length with a streak camera, and to measure the beam quality using a state-of-the-art single photon counting technique. | ||
| TUPCH048 | A Study of Emittance Measurement at the ILC | 1115 |
|
||
| The measurement of the ILC emittance in the ILC beam delivery system and the linac is simulated. Estimates of statistical and machine-related errors are discussed and implications for related diagnostics R&D are inferred. | ||
| TUPCH049 | Proposal for a Fast Scanning System Based on Electro-optics for Use at the ILC Laser-wire | 1118 |
|
||
| Electro-optic devices open the possibility of ultra-fast scanning systems for use in intra-train scanning at the ILC, where scanning rates in excess of 100 kHz may be required. A first study of the possibilities is presented together with the first results from a prototype system. | ||
| TUPCH050 | Beam Profile Measurements with the 2-D Laser-wire | 1121 |
|
||
| A new laser-wire system has been installed at the PETRA ring at DESY, Hamburg. The system is set up to scan in two dimensions using piezo-driven mirrors and employs a newly acquired injection seeded Q-switched laser. The system is described and first results are presented. | ||
| TUPCH052 | Turn by Turn Measurements at DAFNE Based on the Libera Beam Position Processor | 1124 |
|
||
| The BPM detection electronics developed by Instrumentation Techonologies implements digital receivers technology to measure beam position from the amplitude of pick-up signals. Besides the closed orbit mode, the Libera module can be operated also in the Turn-by-Turn mode. Operational experience with Libera at DAFNE, the Frascati e+ e- collider, has been focused on this functionality. Data obtained from DAFNE have been processed with well established extraction algorithms to accurately measure the betatron tunes from a small number of turns, providing instantaneous information on tune variations occurred also in fast damped decays after a kick. Hardware and software implementation together with experimental data are reported. | ||
| TUPCH053 | Bunch Length Characterization Downstream from the Second Bunch Compressor at FLASH DESY, Hamburg | 1127 |
|
||
| The characterization of the longitudinal density profile of picosecond and sub-picosecond relativistic particle bunches is a fundamental requirement in many particle accelerator facilities, since knowledge of the characteristics of the accelerated beams is of utmost importance for the successful development of the next generation light sources and linear colliders. The development of non-intercepting beam diagnostics is thus necessary to produce and control such beams. First experimental evidences of the non-intercepting nature of diffraction radiation diagnostics are given. The longitudinal bunch distribution downstream of the second bunch compressor of the DESY TTF VUV-FEL has been reconstructed using a frequency-domain technique based on the autocorrelation of coherent diffraction radiation. Due to the low and high frequency suppression, introduced by the experimental apparatus, only a portion of the CDR spectrum participates to the reconstruction of the longitudinal bunch profile. The knowledge of the system frequency response is then crucial in order to correct the results and extrapolate a bunch shape as close as possible to the real one. | ||
| TUPCH054 | Upgrade of Signal Processing of the BPM System at the SPring-8 Storage Ring | 1130 |
|
||
| SPring-8 is a third generation synchrotron light source, which is operated stably with top-up mode and with optics of low emittance mode. Along with stabilization of electron beam orbit in the ring, upgrading of the BPM system has also been required. We have developed a new signal processing circuit for COD measurement with a target of a few microns of position resolution at 1 kHz band-width and a few hundreds per second to take beam position of all BPMs. In the new circuit, a multiplexing method is employed and the IF frequency is directory detected with a 2MSPS 16-bit ADC. The digitized signal is processed with DSP to obtain beam position. Analog components of the circuit are equipped in a temperature controlled cabinet in order not to be affected by fluctuation of ambient temperature. In this paper we report schematics and performance of the new circuit, e.g., dependence of position resolution on measurement band-width and long time stability, etc. In addition, we briefly describe possibility of fast orbit measurement as a further application of the circuit. | ||
| TUPCH055 | Beam Phase Measurement of Stored Bunch | 1133 |
|
||
| We developed a system to measure synchronous phase angles for all bunches stored in the storage ring using an oscilloscope with high sampling rate. Precise phase measurement of specific bunch is required from the synchrotron radiation (SR) users, especially from the time resolved spectroscopy users. In a pump and probe experiment, the trigger timing for pumping laser should be precisely adjusted to the probe SR light. The timing of SR light is affected by the accelerating RF voltages, filling pattern, bunch currents, gap positions of insertion devices and so on. At the SPring-8, the bunch currents and the synchronous phase angles for all stored bunches can be measured within 30seconds using newly developed system. The precision of the phase angle is less than 8ps. We are now preparing to deliver the information of synchronous phase angle to SR users. The detail of the measurement system and achieved performance will be presented. | ||
| TUPCH056 | A Simpler Method for SR Interferometer Calibration | 1136 |
|
||
| Previous methods of performing absolute calibration of the SR interferometer used at KEKB (measuring mirror distortion with a pinhole mask, virtual beam broadening via local bumps, physical beam broadening via dispersion bumps) are very time-consuming, and require dedicated machine time to take the necessary data. We report on a new, simpler method we have developed, wherein we create small local bumps at the SR source point and observe the resulting shifts in the phase of the interference fringes. From these data we can calibrate the total magnification of the system, including the effects of mirror distortion. The calibration data can be taken in a very small amount of time (tens of minutes), and in parallel with physics running, without stopping the beam-size measurement system or interfering with its use for luminosity tuning. By taking the calibration data at different beam currents and correlating the magnification at each current with the appropriate interference pattern fit parameters, we can also obtain the parameters needed for real-time mirror distortion correction. | ||
| TUPCH057 | A Diagnostic System for Beam Abort at KEKB | 1139 |
|
||
| A controlled beam abort system has been installed at KEKB for the protection of the hardware components of the accelerator and detector from damage by ampere-class beam currents. In order to identify the reason for each abort and optimize the abort system to handle each type of problem as well as improve machine operation, a diagnostic system has been developed. Fast signals, such as beam currents, accelerating voltages of the RF cavities and beam loss monitor signals from PIN photo-diodes are recorded and analyzed by a data logger system with a high sampling rate at the moment of each abort. Beam oscillations, radiation dose at the detector and vacuum pressure are also examined to classify the reasons for beam loss and aborts. Statistics and typical examples of these aborts will be discussed. | ||
| TUPCH058 | Very Small Beam Size Measurement by Reflective SR Interferometer at KEK-ATF | 1142 |
|
||
| An SR interferometer with the Herschelian reflective optics has been developed for the measurement of several um beam size. The chromatic aberration of the optical system applied in the SR interferometer limits the resolution of SR interferometer. We used objective lens of the SR interferometer by a focusing mirror. For the convenience of observation of the interferogram, we applied Herschelian arrangement of the optics. The measured vertical beam size was less than 5um and the estimated vertical emittance was 1x10-11m at the KEK-ATF damping ring. | ||
| TUPCH059 | Dual-mode Beam Current Monitor | 1145 |
|
||
| A new type HEREWARD-transformer is developed. The original scheme connects pickup coil to the low impedance input of the amplifier to increase the time constant of the transformer. The new scheme employs negative impedance circuit which realizes perfect cancellation of the coil resistance. Therefore DC component of the beam current can be observed. Since number of winding of the pick up coil is only 100-turns, therefore by using the original scheme with a fast operational amplifier, the transformer can be operated at fast CT mode. Thus the dual mode operation can be realized by single core; the first mode is the slow beam intensity monitor, and the second is a fast response transformer. This operation mode realizes an accurate observation of the beam injection process. In order to make installation easy, the core is divided into two pieces. The magnetic shield from bending field is also installed. This monitor is developed at KEK, and installed into the accelerator at the WAKASA WAN Energy Research Center. | ||
| TUPCH060 | Beam Collimator System in the J-PARC 3-50BT Line | 1148 |
|
||
| For the J-PARC 50 GeV Main Ring Synchrotron (MR), the design beam emittance is 54 pi mm mrad. On the other hand, the 3 GeV beam from the Rapid Cycling Booster Synchrotron (RCS) may have a large halo component upto 216 pi mm mrad. In order to absorb the halo component, a beam collimator system will be installed in the beam transport line called as the 3-50BT, which connects the RCS and the MR. From the view of the hands-on maintenance, high endurance structure is adopted. The beam collimator design including the beam optics is reported in this paper. | ||
| TUPCH061 | Installation of Beam Monitor Sensors in the LINAC Section of J-PARC | 1151 |
|
||
| In the LINAC section of J-PARC, we have several type of sensors of monitor, i.e, Beam Position Monitor, Beam Profile Monitor, Beam Size Monitor, Current Monitor, Beam Phase Monitor, Beam Loss Monitor. Those sensors are being installed currently. The procedures, remarks during the installation, status are described in this paper. As an examle, the beam postion monitors are one of sensors which are taken cared intensively for their positioning on their housing quadrupole magnet, then our cares during their installation are described . | ||
| TUPCH062 | Synchrotron Radiation Diagnostics for the NSLS Booster | 1154 |
|
||
| We developed an optical diagnostics system for the NSLS booster-synchrotron utilizing the synchrotron radiation from the dipole magnet. MATLAB based software allows to study the electron beam properties along the energy ramp. The trajectory, beam sizes and coupling at the different instants of time are retrieved from the analysis of the electron beam image. In the paper we present the system layout, as well as experimental results and upgrade plans. | ||
| TUPCH063 | Novel Method for Beam Dynamics using an Alpha Particle Source | 1157 |
|
||
| PRISM is a future muon source which would provide high intense, monochromatic and pure muon beams. In order to achieve such muon beams we use a technique called Phase Rotation using an FFAG ring (PRISM-FFAG). The PRISM-FFAG ring is now under construction in Osaka university. The Commissioning will start in JFY 2007. In order to investigate the dynamical performances of the FFAG before the actual commissioning, we propose a novel experimental method. The principle of the method and its application to PRISM-FFAG will be described in this paper. | ||
| TUPCH064 | Beam-based Alignment Strategy for the Group Controlled Magnets System | 1160 |
|
||
| The beam based alignment of the beam position monitor (BPM) becomes an important tool to reduce the closed orbit distortion (COD) in the recent accelerator. Normally, it requires the independent control of the quadrupole field. Changing the current of a quadrupole magnet, one would find the unperturbed position. However, the J-PARC Rapid-Cycling Synchrotron (RCS) has seven quadrupole families and only group of each family can be controlled simultaneously. There is neither separate power supplies nor auxiliary coil windings on each individual magnet. A similar alignment procedure is applicable for the coupled-controlled magnet system, but it becomes very complicated. For the simplest case, three magnets grouped together, four different beam orbits have to be measured at three different BPM locations. The method and some simulation results for J-PARC/RCS case will be presented in this report. | ||
| TUPCH065 | A Prototype of Residual Gas Ionization Profile Monitor for J-PARC RCS | 1163 |
|
||
| A prototype of a residual gas ionization profile monitor (IPM) for J-PARC RCS has been developed. It consists of electrodes producing electric field to collect ionized ions/electrons, MCP as a signal read-out device, an electron generator to evaluate the gain balance of MCP channels, and a wiggler type magnet producing guiding field. The monitor has been installed in KEK-PS main ring and has been examined using proton beam. At the conference, recent preliminary results of experiments will be reported. | ||
| TUPCH067 | Time-resolved Beam Emittance Measurement of Dragon-I Linear Induction Accelerator | 1166 |
|
||
| A beam emittance diagnostic system of an intense pulsed electron beam (20MeV, 2.6kA, 80ns) based on optical transition radiation is developed. A gated CCD camera is used to get time-resolved result. We develop a timing system to avoid the time jitter, an anti-interference system to avoid the electromagnetic interference, and a C++ code to deal with the experimental data. The measured emittance is about 2000¦Ð.mm.mrad, which is agree with the result of three gradient method. | ||
| TUPCH070 | Development of Beam Profile Monitor for Cyclotron | 1169 |
|
||
| A beam profile monitor was designed and fabricated to measure the beam shape of the cyclotron MC50 beam line at KIRAMS. The sensor module was made of 13 tungsten wires and they were assembled into an array type. The sensor wires whose diameter is 1 mm were placed in parallel with the incident beam, while they were placed in the perpendicular direction to the incident beam in the conventional method. Thus this monitor has a linear actuator to scan whole beam profile, which moves the sensor module from the dormant to measurement position or vice versa. The current output of each sensor was amplified using a trans-resistance amplifier which can measure input current in the range of 1 pA. The amplifier had a resolution of ~ 20 fA, the temperature drift of ~0.5 pA/°C, and the signal-to-noise ratio greater than 80 dB. Various test results of the amplifier and sensor module assembly are given in this paper. The measured current profiles of cyclotron beam line at KIRAMS are also given. | ||
| TUPCH071 | Testing the Silicon Photomultiplier for Ionization Profile Monitor | 1172 |
|
||
| A new kind of photonic device is proposed to be used in the fast operating mode of the ionization profile monitor. A silicon photomultiplier device combines the advantages of photomultipliers and solid-state photo detectors. It provides high sensitivity, wide optical spectrum response, high bandwidth and absence of 1/f noise component. Those parameters are critical in the IPM with fast readout feature, which is developing in GSI in collaboration with ITEP, COOSY, MSU and CRYRING laboratories. Very first investigations were made to obtain detailed parameters of silicon photomultiplier. A testing layout and resulting performance data are presented in this publication. | ||
| TUPCH072 | New Generation Streak Camera Design and Investigation | 1175 |
|
||
|
The only method for electron bunch duration monitoring with a resolution in the order of 10 fs and less is the method of photochronography of the bunch incoherent radiation in the frequency range, for example, of visible light and at realizing streak camera with new principles of its operation*. In the paper the streak camera design for measuring both the electron bunches and x-ray pulses duration with the mentioned temporal resolution is presented. The results of the camera investigation, with photoelectron dynamics simulation taking into account space-charge effect and impact of the surface roughness of a spherical photocathode of the 20-50 micrometers radius (forming a modulating gap of spherical configuration) on the camera resolution, are presented and discussed.
*A. M. Tron and I. G. Merinov. Method of bunch radiation photochronography with 10 femtosecond and less resolution. http://www.physics.ucla.edu/PAHBEB2005/talks/10oct2005/wg2/atron.pdf |
||
| TUPCH073 | Study of Beam Energy Spread at the VEPP-4M | 1178 |
|
||
|
The knowledge of beam energy spread is necessary for the experimental program of the VEPP-4M collider. In this report we discuss the application of optical diagnostics for measurement of this value. The diagnostics is based on multi-anode photomultiplier and provides information about betatron and betetron frequencies of electron beam*. The beam energy spread is derived from the spectra of synchrotron oscillation. The results, obtained with this method, are compared with data, provided by Compton backscattering technique.
*O. I. Meshkov et al. Application of the beam profile monitor for VEPP-4M tuning. Proc. of DIPAC '05, June 6 - 8, 2005, Lyon, France, POM008. |
||
| TUPCH074 | Fast and Precise Beam Energy Monitor Based on the Compton Backscattering at the VEPP-4M Collider | 1181 |
|
||
| Accurate knowledge of the colliding beam energies is essential for the current experiments with the KEDR \cite{KEDR} detector at the VEPP-4M collider. Now the experimental activity is focused on the new precise measurement of the tau-lepton mass by studying the behavior of the tau production cross-section near the reaction threshold. To achieve the desired quality of the experiment, an on-line beam energy monitoring by the Compton backscattering of laser light was performed. This approach is found to be a very good supplement to rare energy calibrations by the resonant depolarization technique, saving the beam time for luminosity runs. The method itself does not require electron beam polarization and additionally allows one to measure the electron beam energy spread. The achieved accuracy of the method in the beam energy range 1.7–1.9 GeV is 60 keV. | ||
| TUPCH075 | Dependence of the Electron Beam Polarization Effect in the Intra-beam Scattering Rate on the Vertical Beam Emittance | 1184 |
|
||
| Measurement of the Intra-beam scattering rate is applied in the resonant depolarization technique to detect beam polarization in electron/positron storage rings. A depolarization jump in the counting rate of scattering particles occurs at the instant when the beam becomes unpolarized due to fulfillment of the external spin resonance condition. The magnitude of the jump depends on polarization quadratically. It also depends on some other beam parameters as well as the position of counters relative to the beam orbit. A larger jump implies higher accuracy in absolute calibration of particle energy because the latter is proportional to the spin precession frequency. In contrast to an ordinary one-dimensional approach, we calculate the magnitude of jump subject to, among other things, the vertical component of relative velocity in particle collisions inside the beam. For this purpose, the transverse momentum distribution function is properly modified. Calculations performed for the VEPP-4M storage ring-collider show that the jump may depend significantly on the ratio between the vertical and radial beam emittance. We present results of our recent experiments on study of this dependence. | ||
| TUPCH077 | Beam Phase Measurement in a 200 MeV Cyclotron | 1187 |
|
||
| New phase measuring equipment is being planned for the K 200 variable frequency, separated-sector cyclotron at iThemba LABS near Cape Town. A commercial lock-in amplifier is used to measure the beam phase over the full radial range. Measurements are made at the third and fifth harmonics of the main RF frequency to limit pick-up from the flat-topping and main dees. Computer-generated signals, with phase and amplitude control, at the same harmonics, are used to cancel the signals coupled from the dees to the phase probes. In addition the signals without beam are vectorially subtracted from those with beam to enhance the sensitivity and accuracy. Results of measurements, using these techniques, on existing phase probes in the cyclotron, will be presented. | ||
| TUPCH078 | BPM Design for the ALBA Synchrotron | 1190 |
|
||
| ALBA is a 3 GeV, low emittance, 3rd generation synchrotron light source that is in the construction phase in Cerdanyola, Spain. Vertical beam sizes down to a few microns will require beam stabilities on the submicron level. The BPM has to be designed in order to provide reliable and accurate beam position readings. Simulation and computational codes have been used to optimise, for a given vacuum chamber dimension, the BPM design. The optimisation has taken into account the usual sensitivity and intrinsic resolution parameters, but as well, the wakefield loss factor of the buttons. Due to the small vertical vacuum chamber dimension and the high design current, the beam power deposited in the buttons is becoming a concern due to the thermal deformation effects that can introduce errors at the submicron level. A compromise between a higher intrinsic resolution from one side, and a low power deposited by the beam in the buttons from the other, define the final buttons dimensions. | ||
| TUPCH079 | Characterisation of the MAX-II Electron Beam: Beam Size Measurements | 1193 |
|
||
| Over the last year investigations of the MAX-II electron beam characteristics have been made. Examples of investigated parameters include the beam size, bunch length, vacuum and Touschek lifetimes, and the machine functions. Several upgrades of the MAX II ring have been performed since the commissioning 1995 like a new 100 MHz RF system with a 500 MHz Landau cavity, exchanged injector, and a variety of insertion devices. There is hence a need to systematically characterize the present machine. This systematic characterisation is now underway and this article describes details of the beam size measurements. | ||
| TUPCH080 | Bunched Beam Current Measurements with 100 pA rms Resolution at CRYRING | 1196 |
|
||
| In CRYRING molecular beams with currents down to 1 nA are used for experiments. To extend the rms resolution of the bunched beam current measurements down to 100 pA, a BERGOZ Integrating Current Transformer (ICT) and one of the the capacitive pick-up's sum signal are integrated simultaneously. The absolute calibration of the pick-up integrator signal is carried out at the end of the acceleration stage, during 20-60 ms. The ion beam current can be measured over a pulse width range of 100 ns to 15 us with a 20-60% bunch duty cycle. For both detectors, low noise amplifiers and a differential input double integrator have been designed. A programmable phase shifter allows measurement of the beam current during the acceleration of the ions, generating a gate signal with proper phase for the integrators in the 30 kHz-3 MHz frequency range. The bandwidth of the integrators used is 100 Hz. | ||
| TUPCH081 | Technical Aspects of the Integration of the Optical Replica Synthesizer for the Diagnostics of Ultra-short Bunches in FLASH at DESY | 1199 |
|
||
|
In this paper we present an overview of current status of the Optical Replica synthesizer at DESY. The method is based on producing an "optical copy" of the electron bunch with its subsequent analysis with optical techniques*. To this end, a near-IR laser beam is superimposed on the electron beam in the first undulator of an optical klystron. In the following dispersive section the laser-induced energy modulation is transformed into a density modulation . The modulated electron bunch then produces a strong optical pulse in the second undulator. Analysis of this near-IR pulse (the optical copy) then provides information about the profile, the slice emittance and the slice energy spread of the electron bunch. We discuss the implementation of such a measurement set-up at the FLASH facility at DESY and investigate the influence of various parameters on the performance of the device. Topics we address include the dispersive chicane, as well as the requirements for the seed laser pulses and the detection and analysis of the near-IR pulse.
*E. Saldin, et al. "A simple method for the determination of the structure of ultrashort relativistic electron bunches," Nucl. Inst. and Methods A 539 (2005) 499. |
||
| TUPCH082 | The EuroTeV Confocal Resonator Monitor Task | 1202 |
|
||
| We describe the progress in the analysis of the confocal resonator monitor task which is part of the diagnostics workpackage of EuroTeV. The initial design was analyzed both numerically and experimentally and found limitations. We therefore digressed from strict confocality and report the numerical analysis and S-parameter measurements of a modified design. Furthermore, we discuss the mechanical design needed for planned tests with beam in CTF3 which requires integration of the monitor into the beam pipe, damping of trapped modes, and frequency tunability. | ||
| TUPCH083 | Time-resolved Spectrometry on the CLIC Test Facility 3 | 1205 |
|
||
| The high charge (>6microC) electron beam produced in the CLIC Test Facility 3 (CTF3) is accelerated in fully loaded cavities. To be able to measure the resulting strong transient effects, the time evolution of the beam energy and its energy spread must be measured with at least 50MHz bandwidth. Three spectrometer lines were installed all along the linac in order to control and tune the beam. The electrons are deflected by a dipole magnet onto an Optical Transition Radiation (OTR) screen, which is observed by a CCD camera. The measured beam size is then directly related to the energy spread. In order to provide time-resolved energy spectra, a fraction of the OTR photons is sent onto a multichannel photomultiplier. The overall set-up is described, special focus is given to the design of the OTR screen with its synchrotron radiation shielding. The performance of the time-resolved measurements are discussed in detail. Finally, the limitations of the system, mainly due to radiation problems, are discussed. | ||
| TUPCH084 | Expected Signal for the TBID and the Ionization Chambers Downstream of the CNGS Target Station | 1208 |
|
||
| Downstream the carbon graphite target of the CNGS (CERN Neutrinos to Gran Sasso) facility at CERN it has been decided to install a secondary emission monitor called TBID (Target Beam Instrumentation Downstream) monitor to measure the multiplicities and the left/right as well as up/down asymmetries of secondary particles from target. Calculations show that the titanium windows used to close off the TBID vacuum tank might not withstand the highest beam intensities with small spot sizes expected at CNGS, in case the proton beam accidentally misses the 4-5 mm diameter target rods. Therefore it has been suggested to place two ionisation chambers as a backup for the TBID located left and right of the TBID monitors. Monte Carlo simulations with the particle transport code FLUKA were performed firstly to obtain the fluence of charged particles in the region of interest and secondly to estimate the induced radioactivity (noise) in this area. This allows to assess the actual signal/noise situation and thus to determine the optimal position (lateral displacement with respect to the beamline) of the ionisation chambers. This document presents the results of these calculations. | ||
| TUPCH086 | Precision Beam Timing Measurement System for CLIC Synchronization | 1211 |
|
||
| Very precise synchronization between main and drive beams is required in CLIC to avoid excessive luminosity loss due to energy variations. One possibility to accomplish this would be to measure and correct the drive beam phase. The timing reference for the correction could be the beam in the transfer line between the injector complex and the main linac. The timing of both main and drive beams will have to be measured to a precision in the region of 10 fs. The aim is to achieve this by means of a beam measurement at 30 GHz with the signal mixed down to an intermediate frequency (IF) for precise phase detection. The RF and IF electronics are being developed and tests will be carried out in CTF3. | ||
| TUPCH087 | Beam Diagnostics with Schottky Noise in LEIR | 1214 |
|
||
| The high density Lead ion beams, needed for LHC, are obtained in the Low Energy Ion Ring (LEIR) at CERN by multi-turn injection followed by electron cooling and stacking. During this injection and stacking phases where the circulating beam is unbunched, diagnostics with Schottky noise are used for probing essential beam parameters, such as tune, momentum spread, emittance and their evolution with time… The hardware facility and first results obtained during the recent commissioning of LEIR are described. | ||
| TUPCH088 | High Dynamic Range Beam Profile Measurements | 1217 |
|
||
| In future high intensity, high energy accelerators, beam loss has to be minimized to maximize performance and minimize activation of accelerator components. It is imperative to have a clear understanding of the mechanisms that can lead to halo formation and to have the possibility to test available theoretical models with an adequate experimental setup. Measurements based on optical transition radiation (OTR) provide an interesting opportunity for high resolution measurements of the transverse beam profile. In order to be applicable for measurements within the beam halo region, it is of utmost importance that a high dynamic range is covered by the image acquisition system. The existing camera system as it is installed in the CLIC Test Facility (CTF3) is compared to a step-by-step measurement with a photo multiplier tube (PMT) and measurements with a cooled charge injection device (CID) camera. The latter acquisition technique provides an innovative and highly flexible approach to high dynamic range measurements and is presented in some detail. | ||
| TUPCH089 | Investigations of OTR Screen Surfaces and Shapes | 1220 |
|
||
| Optical transition radiation (OTR) has proven to be a flexible and effective tool for measuring a wide range of beam parameters, in particular the beam divergence and the transverse beam profile. It is today an established and widely used diagnostic method providing linear real-time measurements. Measurements in the CLIC Test Facility (CTF3) showed that the performance of the present profile monitors is limited by the optical acceptance of the imaging system. In this paper, two methods to improve the systems' performance are presented and results from measurements are shown. First, the influence of the surface quality of the OTR screen itself is addressed. Several possible screen materials have been tested to which different surface treatment techniques were applied. Results from the measured optical characteristics are given. Second, a parabolic-shaped screen support was investigated with the aim of providing an initial focusing of the emitted radiation and thus to reduce the problem of aperture limitation. Measured and calculated emission distributions are presented. | ||
| TUPCH090 | Electron Beam Profile Measurements with Visible and X-ray Synchrotron Radiation at the Swiss Light Source | 1223 |
|
||
| Two different methods of beam profile measurements using a) visible-to-UV range synchrotron radiation b) X-ray synchrotron radiation have been realized in a single diagnostics beam line at the Swiss Light Source. While the visible-to-UV part uses a focusing lens to create an image of the electron beam cross section, the X-ray part makes use of the pinhole camera principle. In the visible-to-UV case the vertically polarized synchrotron radiation renders an image heavily influenced by inherent emission and diffraction effects of synchrotron radiation. This turns out to be an advantageous influence in order to determine ultra small beam profiles. For each of the two methods practical point-spread function measurements, including all beam line components, and high-precision wave-optics based calculations (SRW code) of the synchrotron light characteristics were performed to ensure correct interpretation of the measured profiles. Results from both monitors will be presented to allow comparison. | ||
| TUPCH092 | Commissioning of a New Digital BPM System for the PSI Proton Accelerators | 1226 |
|
||
| A new digital beam position monitor (DBPM) system has been developed and successfully tested at the PSI proton accelerators. The DBPM hardware consists of an analogue RF front-end (RFFE), a VMEbus backplane module (VBM), and the PSI VME PMC Carrier board (VPC). The RFFE combines the 2nd RF harmonic (101.26 MHz) beam signals of pickup coils with a 101.31 MHz pilot signal. The RFFE output signals are undersampled and down-converted to base-band (no analogue mixer) by ADCs and DDCs (Direct Digital Downconverters) on the VBM. The DDCs send the digitised beam and pilot signal amplitudes to a Virtex2Pro FPGA on the VPC board. The FPGA calculates the beam positions at different averaging rates, checks interlock limits, and provides triggered storage of beam position waveforms. Furthermore, the FPGA performs automatic gain control of voltage-controlled amplifiers (VCAs) of RFFE and VBM. By continuous normalisation of beam to pilot signal, nonlinearities and temperature drifts of the electronics are eliminated. Compared to the old analogue BPM electronics, the new DBPMs offer an increased dynamic range (0.2 μA to 2 mA instead of 5 μA to 2 mA) and larger bandwidth (10 kHz instead of 10 Hz). | ||
| TUPCH094 | THz Diagnostic for the Femtosecond Bunch Slicing Project at the Swiss Light Source | 1229 |
|
||
| Interaction of electron bunches with a femtosecond Ti:Sa laser beam along a modulator wiggler in the Swiss Light Source (SLS) storage ring results in an energy modulation of the electron beam on the length scale of the laser pulse. While high energy photon pulses (3 18 keV, ~ 100 fs long) are produced by an in-vacuum undulator (radiator) and used for time resolved experiments within the SLS femtosecond bunch slicing project, coherent synchrotron radiation (CSR) emitted by the adjacent bending magnet in the THz-regime is used for longitudinal slicing diagnostics and monitoring of slicing efficiency. This paper describes the simulation and layout of the THz-diagnostic beamline and presents first time and spectrally resolved measurements with the longitudinal slicing diagnostics, which has been set-up for the SLS “femto-slicing” project. | ||
| TUPCH095 | Status of Synchrotron Radiation Monitor at TLS | 1232 |
|
||
| Synchrotron radiation monitor of the Taiwan Light Source have been upgraded recently. Improvement of optics and modelling was performed to improve accuracy of measurement for small beam size. Synchrotron light interferometer is implemented for complementary measurement. IEEE-1394 digital CCD camera is used to improve image transmission quality, camera remote control and to extend dynamic range. Intensify gated camera are included in this upgrade for dynamic property observation of the stored beam. Functionality enhancement of image analysis is also supported. Efforts and achievements will be summarized in this report. | ||
| TUPCH096 | High-intensity Bremsstrahlung Monitoring System for Photonuclear Technologies | 1235 |
|
||
| The realization of promising photonuclear technologies (a soft technology for medical isotope production, radioactive waste handling, activation analysis, etc) calls for the sources of high-energy (Egamma>10MeV) and high-intensity (>=10E03W/cm2) photons. These sources may by obtained by converting a beam from a high-current electron Linac into bremsstrahlung. The method of combined activation of a set of foils that have different energy thresholds of the (gamma,n) reactions is proposed to determine the space-energy characteristics of such radiation. In each energy range the geometrical characteristics of the bremsstrahlung flux are reconstructed from the foil surface gamma-activity distribution. The last one is determined through one-dimensional scanning of the foils by a specially designed detecting head that includes a linear matrix of 16 collimated semiconductor detectors (CdZnTe; 2x2x2,mm). A preliminary analysis of the system geometry and applicability of the method was performed by computer simulation based on the PENELOPE software. A developed PC based measuring system with CAMAC interface is described. | ||
| TUPCH097 | Instrumentation and Operation of a Remote Operation Beam Diagnostics Lab at the Cornell Electron-positron Storage Ring | 1238 |
|
||
| Accelerator beam diagnostics are being modified at the Laboratory of Elementary Particle Physics (LEPP) at Cornell University for remote operation at nearby Alfred University. Presently, a streak camera used for longitudinal dynamics measurements on the Cornell Electron-Positron Storage Ring (CESR) is operational and measurements have been made from Alfred University [1]. In the near future, photomultiplier tube arrays for electron and positron vertical beam dynamics measurements will be remotely operated as well. In this paper, we describe instrumentation and operation of the remote beam diagnostics. | ||
| TUPCH098 | Antiproton Momentum Distributions as a Measure of Electron Cooling Force at the Fermilab Recycler | 1241 |
|
||
| The Fermilab Recycler is a fixed 8GeV kinetic energy storage ring located in the Fermilab Main Injector tunnel near the ceiling. Electron cooling of high-energy antiprotons has recently been demonstrated at the Recycler. Antiproton beam Schottky signals were used to measure the antiproton momentum distribution at equilibrium between a calibrated broadband diffusion source and electron cooling. The large Recycler momentum aperture, the dependence of the electron cooling force as a function of the antiproton momentum deviation and the calibrated diffusion source combine to give a unique spectral measurement of the antiproton momentum beam distribution. | ||
| TUPCH099 | Development of HOM Damped Copper Cavity for the ESRF | 1244 |
|
||
|
At the ESRF, HOM driven longitudinal coupled bunch instabilities are currently avoided up to the nominal beam current of 200 mA by precisely controlling the cavity temperatures and thereby the HOM frequencies of the existing five-cell copper cavities. A bunch-by-bunch feedback is presently being commissioned in order to increase the maximum stored current. In parallel, normal conducting strongly HOM damped cavities are under study to possibly replace the five-cell cavities. The design is based on a scaling of the single cell EU cavity*: a pillbox geometry with nose cones and three attached ridged waveguides loaded by ferrites for effective HOM damping. We report on the electromagnetic simulation making use of the 3D codes HFSS and GdfidL. They allowed optimizing the shape of both cavity and dampers, including electromagnetic absorbing material with frequency dependent parameters.
*E. Weihreter et al. A Ridged Circular Waveguide Ferrite Load for Cavity HOM Damping, this conference. |
||
| TUPCH100 | Fiberoptics-based Instrumentation for Storage Ring Longitudinal Diagnostics | 1247 |
|
||
| Many beam diagnostic devices in today's synchrotron rings make use of the radiation emitted by the circulating particles. Such instruments are placed in close proximity of the accelerator, where in many instances they cannot be easily accessed for safety consideration, or at the end of a beamline, which because of its cost, can only move the light port a few meters away from the ring. We present a study on the coupling of synchrotron light into an optical fiber for all those application where the longitudinal properties of the beam are measured (i.e., bunch length, phase, intensity, etc.). By choosing an appropriate fiber it is possible to keep attenuation and dispersion at negligible values over a large bandwidth, so that this method would allow to have the diagnostic instruments directly in the control room, or wherever convenient, up to several hundred of meters away from the tunnel. This would make maintaining and replacing instruments, or switching between them, possible without any access to restricted areas. Additionally, the few components required to be near the ring (lenses and couplers) in order to couple the light into the fiber are intrinsically radiation-hard. | ||
| TUPCH101 | Modeling of Ultrafast Streak Cameras | 1250 |
|
||
| We present progress on modeling of streak camera with application to measurement of ultrafast phenomena. Our approach is based on treating the streak camera as a photocathode gun and applying modeling tools for beam optics, space charge, and electromagnetic fields. We use these models to compare with experimental results from a streak camera developed at the Advanced Light Source. Furthermore, we explore several ideas for achieving sub-100 fsec resolution. | ||
| TUPCH103 | New Developments on Single-shot Fiber Scope | 1253 |
|
||
| New development has been done to reduce the noise and improve the stability of the single-shot fiber scope, which used an optical fiber recirculating delay line to regenerate the single-shot very short electrical pulse, so a sampling scope can recover the original signal. New measurements have been done and will be reported. | ||
| TUPCH105 | Performance of a Nanometer Resolution BPM System | 1256 |
|
||
| International Linear Collider (ILC) interaction region beam sizes and component position stability requirements will be as small as a few nanometers. It is important to the ILC design effort to demonstrate that these tolerances can be achieved – ideally using beam-based stability measurements. It has been estimated that RF cavity beam position monitors (BPMs) could provide position measurement resolutions of less than one nanometer and could form the basis of the desired beam-based stability measurement. We have developed a high resolution RF cavity BPM system. A triplet of these BPMs has been installed in the extraction line of the KEK Accelerator Test Facility (ATF) for testing with its ultra-low emittance beam. The three BPMs are rigidly mounted inside an alignment frame on variable-length struts which allow movement in position and angle. We have developed novel methods for extracting the position and tilt information from the BPM signals including a calibration algorithm which is immune to beam jitter. To date, we have been able to demonstrate a resolution of approximately 20 nm over a dynamic range of ± 20 microns. We report on the progress of these ongoing tests. | ||
| TUPCH106 | Commissioning the SPEAR3 Diagnostic Beamlines | 1259 |
|
||
| SPEAR 3 has two diagnostic beam lines: an x-ray pinhole camera and a visible/UV laboratory. The pinhole camera images ~8 keV dipole radiation on a phosphor screen with a remote computer to capture digital profile images. The visible/UV beam line features an 8 mm high GlidCop 'cold finger' to remove the x-ray core of the beam. The remaining light is deflected horizontally onto an optical bench where it is focused via reflective (Cassegrain) or refractive optics. The visible beam is then split into branch lines for a variety of experimental applications. This paper describes the experimental arrangement, data processing algorithms and measurements obtained with both systems. | ||
| TUPCH108 | Characterization of the PEP-II Colliding-beam Phase Space by the Boost Method | 1262 |
|
||
| We present a novel approach to characterize the colliding-beam phase space at the interaction point of the energy-asymmetric PEP-II B-Factory. The method exploits the fact that the transverse-boost distribution of e+ e- –> mu+ mu- events reconstructed in the BaBar tracking system, reflects that of the colliding electrons & positrons. The average boost direction, when combined with the measured orientation of the luminous ellipsoid, determines the e+e- crossing angles. Varying the horizontal direction of one beam with respect to the other in a controlled fashion allows to estimate the individual e+ and e- horizontal IP beam sizes. The angular spread of the transverse boost vector provides an accurate measure of the angular spread of the incoming high-energy beam, confirming the presence of a significant beam-beam induced increase of this angular spread. In addition, the longitudinal dependence of the angular spread of the boost vector in the y-z plane allows to extract from the continuously-monitored boost distributions, a weighted average of the vertical IP beta-functions & emittances of the two beams representative of routine high-luminosity operation. | ||
| TUPCH109 | Ion-related Phenomenon in UVSOR/UVSOR-II Electron Storage Ring | 1265 |
|
||
|
A vertical betatron tune shift depending on beam current under multibunch condition was observed in the UVSOR storage ring. Vertical tune increased as beam current decreased, and the slope of the tune shift depended on the condition of the vacuum in the ring. Such a change in vertical tune was explained by a change in the stability condition of trapped ions*/** with the beam current. Based on a theoretical model*** that gives density of the trapped ions the experimental results were discussed via analytic and tracking calculations. Both the effect from the residual gas ions generated by scattering between high energy electrons and molecules and that from dissociated ions that come from secondary ionization processes have been discussed. In quest of the ion-related phenomenon in single-bunch condition, precise tune measurement has been also performed in the UVSOR-II storage ring. The experimental results in the single-bunch condition have been discussed. Precise measurement of vacuum pressure in the beam duct is a key issue of the ion-related phenomenon. A design of vacuum pressure measurement system via detecting residual gas fluorescence will be introduced in the presentation.
*R. D. Kohaupt. DESY Internal. Bericht No.H1-71/2 (1971). **Y. Baconnier and G. Brianti. CERN Internal Report No.CERN/SPS/80-2(DI) (1980). ***A. Mochihashi et al. Jpn. J. Appl. Phys. 44 (2005) 430. |
||
| TUPCH110 | Upgrade of Main RF Cavity in UVSOR-II Electron Storage Ring | 1268 |
|
||
|
The UVSOR electron storage ring, which is dedicated to a synchrotron radiation (SR) light source especially for VUV and Soft X-ray, has been improved at the beginning of 2003, and transverse emittance in the improved ring (UVSOR-II)* has been decreased from 165nm-rad to 60 and/or 27nm-rad. Users runs have been performed since September 2003 with 60nm-rad mode, and since then high brilliant SR beams have been supplied routinely for users. The 27nm-rad mode, however, was difficult to introduce to daily operation initially because Touschek lifetime was insufficient in such small emittance condition. To improve the beam lifetime and make full use of the SR beams, we have built new main RF cavity. The aim of the improvement was to increase momentum acceptance by increasing RF accelerating voltage; the previous cavity generated the voltage of 55kV, whereas the new one can generate 150kV in maximum without changing RF frequency (90.1MHz) and transmitter (20kW in maximum). The new cavity has been installed in the UVSOR-II in spring of 2005, and high power commissioning went on smoothly. Because of the improvement, from spring 2005 the UVSOR-II has switched the daily users run to 27nm-rad.
*M. Katoh et al., in this conference. |
||
| TUPCH111 | RF System for the Superconducting Linac Downstream from DEINOS Injector | 1271 |
|
||
| The DEINOS injector will be followed by an accelerator consisting of a LEP-like cryomodule including four 4-cell superconducting cavities. Each of these cavities will be fed by a solid-state amplifier delivering 20 kW in CW operation at 352 MHz. We will use the technology developed by the "Synchrotron SOLEIL" RF team, consisting of merging the power of numerous independent 330 W modules. The design of the low level RF system will be based on our experience with the ELSA accelerator. | ||
| TUPCH112 | Commissioning of the 100 MeV Preinjector HELIOS for the SOLEIL Synchrotron | 1274 |
|
||
| HELIOS is the 100 MeV electron linac pre-injector of SOLEIL the new French SR facility. It has been supplied by THALES, as a turn-key system on the basis of SOLEIL APD design. The linac was commissioned in October 2005. This paper will remind the main features of the linac, especially on beam-loading compensation, and will give results obtained during the commissioning tests where a special care has been taken for emittance measurements. Specified and measured beam parameters will be compared to show the performance of the entire system. | ||
| TUPCH113 | Construction of the ALPHA-X Photo-injector Cavity | 1277 |
|
||
| We will describe the construction and low power testing of an RF cavity to be used as a photo-injector for the ALPHA-X project within the Department of Physics at the University of Strathclyde (UK). The gun is a two and a half cell S-band cavity, employing a metallic photo-cathode. RF power is coupled to the gun via a co-axial power coupler. The specification of the gun and the low power measurements made to achieve the correct mode frequency and field flatness will be presented. | ||
| TUPCH114 | A Ridged Circular Waveguide Ferrite Load for Cavity HOM Damping | 1280 |
|
||
| A normal conducting HOM damped 500 MHz prototype cavity has been tested with three tapered circular double ridged waveguide to coaxial transitions as HOM couplers, featuring maximum longitudinal and transverse HOM impedances below 5 kOhm and 200 kOhm/m respectively. Numerical simulations indicate that these impedance levels can be further reduced by more than a factor of 3 using homogeneous circular double ridged waveguides for improved coupling to the HOMs. In the present paper the layout of an optimised homogeneous waveguide with "in vacuum" ferrite tiles is presented, including mechanical and thermal design considerations. Low power reflectrometry measurements demonstrate good matching of a prototype load, and high power tests of the ferrite absorber elements indicate that the waveguide load is well suited for the cavity HOM power levels present in state of art 3rd generation SR sources. | ||
| TUPCH115 | Status of the 70 MeV, 70 mA CH Proton-DTL for FAIR | 1283 |
|
||
| The CH-type cavity shows promising features in the low and medium beta range: its high accelerator gradient and the high level of shunt impedance together with the compact transverse dimensions make this new cavity a good candidate for proton acceleration up to 100 MeV. That's why GSI has decided to base the new high current proton injector for the new FAIR facility on that structure: the operating frequency will be 352 MHz with an injection energy of 3 MeV. In order to improve the technical experience on this new kind of structure, IAP has built a model consisting of 8 equidistant gaps for a total cavity-length of 60 cm. Several design options with respect to welding, alignement, cooling and RF joints were studied and compared each other. A new concept for the end-cells geometry will result in the desired flatness of the electric field along the cavity axis and, at the same time, allow effective integration of internal quadruple lenses. Finally, the electric quadruple content of CH-structure gaps is listed in dependence on the geometry of the cell. | ||
| TUPCH116 | Waveguide Distribution Systems for the European XFEL | 1286 |
|
||
| In the European X-ray FEL 32 superconducting cavities are connected to a 10 MW multibeam klystron through a waveguide distribution system. The basic waveguide system is a linear system. The XFEL tunnel has limited space for the waveguide system and therefore some new compact high power waveguide components like a motor driven phaseshifter, an iris tuner and an asymmetric shunt tee have been developed. Also alternative layouts of the waveguide distribution system which may have certain advantages have been designed. In this report we will present the different layouts and report on the status of the development of the different new waveguide components. | ||
| TUPCH117 | Experience with the 208MHz and 52MHz RF Systems for the HERA Proton Accelerator | 1289 |
|
||
| The RF System for the Hera Proton Ring consists of four 208MHz systems and two 52MHz systems. At injection three of the 208MHz systems are at 70 kV and one System is at 190kV with a phase of 180 degree. The 52 MHz Systems are at 70kV each. During ramping the RF voltage of all cavities follows a ramp table. At flat top at 920GeV both 52 MHz systems are at 50kV and three of the 208MHz Systems are at 190kV while the 180 degree phased system is reduced to 30kV. The typical beam current is 100mA in 180 bunches with a bunch separation of 96 ns. About one year before shutdown of HERA this presentation gives an review of about 14 years operation of the Proton RF System. It is also an overview of the hardware including the beam loading compensation (fast feedback) the tuning system and the other components. | ||
| TUPCH118 | Manufacturing and Testing of 2.45 GHz and 4.90 GHz Biperiodic Accelerating Structures for MAMI C | 1292 |
|
||
|
At the Institut fur Kernphysik (IKPH) of Mainz University the fourth stage of the Mainz Microtron (MAMI), a 855MeV to 1500MeV Harmonic Double Sided Microtron*, is now on the verge of first operation. For this project ACCEL Instruments GmbH manufactured biperiodic, on axis coupled, standing wave accelerating structures at the frequencies of 2.45GHz and 4.90GHz. Four resp. eleven multicell sections were manufactured, low power characterized and after delivery tested at the high power test stand of IKPH. This paper describes the production and characterization of these structures, presents results of the high power tests, and compares these data with results gained at IKPH for an in house built 4.90GHz prototype and the 2.45GHz structures built in the 1980s.
*A. Jankowiak et al. "Design and Status of the 1.5 GeV-Harmonic Double Sided Microtron for MAMI", Proceedings EPAC2002, Paris, p. 1085. |
||
| TUPCH120 | The Diamond Light Source Booster RF System | 1295 |
|
||
| The Diamond Light Source (DLS) accelerator complex can be divided into three major components; a 3 GeV 561 m circumference storage ring, a 158.4 m circumference full-energy booster synchrotron and a 100 MeV pre-injector linac. This paper describes the design and presents commissioning results of the RF system for the booster synchrotron. Booster RF commissioning took place in late 2005 and early 2006 and involved the setting-into-operation of a 60 kW IOT amplifier, supplied by Thales Broadcast and Multimedia, a 5-cell copper cavity, manufactured by Accel Instruments, and a low-level RF system designed and built by Sincrotrone Trieste SCpA. | ||
| TUPCH121 | The IASA Cooling System for the 10 MeV Linac | 1298 |
|
||
| A de-ionized water cooling system for the IASA room temperature 10 MeV CW Linac has been constructed and successfully installed. Commissioning is undergoing achieving resistivity larger to 5M?cm with a temperature accuracy of for all three linacs. Three ways mixing valves with a stepping capability of one thousand different mixing steps fulfill independently for each section the required temperature stability and the appropriate resonance frequency to our cavities. The RF requirements for the three linacs is 190kW provided by a single high power klystron tube capable to deliver up to 500 kW CW at 2380 MHz. The klystron is been cooled with a parallel similar cooling system and a third system cools our Aluminum waveguide complex. In this paper we will present the design, specifications and results of our preliminary tests. A sophisticated control and interlock system based on EPICS guarantees the proper functioning of the system. | ||
| TUPCH123 | Dipole Stabilizing Rods System for a Four-vane RFQ: Modeling and Measurement on the TRASCO RFQ Aluminum Model at LNL | 1301 |
|
||
| The Dipole Stabilizing Rods (DSR's) are devices used in order to reduce a priori the effect of perturbation on the operating mode of a four-vane RFQ caused by neighboring dipole modes by increasing the frequency spacing between the TE210 mode and dipole modes, without, in principle, affecting the quadrupole TE210 mode. They have proven to be particularly useful in the case of coupled RFQ's whose overall length is significantly greater than the operating wavelength. In this article we present a circuit model of such DSR's, that, used in combination with a transmission line model of a four vane RFQ, has allowed us to predict the dimensioning of the DSR's in the case of the aluminum model of TRASCO RFQ. The DSR parameters and, in general, the accuracy of the model have been also confirmed by HFSS simulations and by RF measurements on the above-mentioned model. | ||
| TUPCH124 | Improvement of Co-based Amorphous Core for Untuned Broadband RF Cavity | 1304 |
|
||
| We have developed a cobalt-based amorphous core as a new magnetic-alloy (MA) core for the loaded RF cavity. Because of its permeability found to be approximately twice as high as that of FINEMET, this MA core is an excellent candidate for constructing a compact broadband RF cavity with less power consumption. In this report, we present our recent studies of the Co-based amorphous core's physical properties and performance. Improvement of the new core coated by new materials surface of ribbon is also described. | ||
| TUPCH126 | Outgassing Rate of Highly Pure Copper Electroplating Applied to RF Cavities | 1307 |
|
||
| We plan to apply a new copper electroplating with a high purity and a high electric conductivity to normal-conducting RF cavities for electron or positron storage rings with a high current beam. As reported in 2005 Particle Accelerator Conference, our first test cavity, made of iron, with the electroplated copper surface finished up by electropolishing showed an excellent electric performance compared with the case of cavities made of oxygen free copper. Our next step is to examine the vacuum performance. This paper reports results of the outgassing-rate measurements on our second test cavity together with its fabrication process. | ||
| TUPCH127 | Fine Grooving of Conductor Surfaces of RF Input Coupler to Suppress Multipactoring | 1310 |
|
||
| An RF input coupler to feed high power into an accelerating cavity with heavy beam loading undergoes many multipactoring zones due to the wide range of the input RF power. Furthermore, a regular coaxial line is more subject to multipactoring than a rectangular waveguide because of the uniformity of the electromagnetic field. Grooving the conductor surfaces of the coaxial line is a promising method to suppress multipactoring under any conditions expected in the above cases. This paper reports results of our multipactoring simulation study and the high power test of the input coupler with a grooved coaxial line. | ||
| TUPCH128 | New Cutting Scheme of Magnetic Alloy Cores for J-PARC Synchrotrons | 1313 |
|
||
| A new cutting method using a grindstone was developed to manufacture the magnetic alloy cores. The problem of local temperature rise around the cut surfaces was solved. Long-term high-power tests have been performed for both J-PARC RCS and MR RF systems. Mechanism of local heating, new cutting scheme, and manufacturing method are presented. | ||
| TUPCH129 | Conceptual Design of a 3rd Harmonic Cavity System for the LNLS Electron Storage Ring | 1316 |
|
||
| The installation of a second RF cavity in the UVX electron storage ring at the Brazilian Synchrotron Light Laboratory (LNLS) at the end of 2003 brought about longitudinal instabilities driven by one of the HOMs of the new cavity. Even though the operational difficulties related to these unstable modes were successfully overcome by means of a combination of cavity tuning (using temperature and plunger adjustments) with phase modulation of the RF fields at the second harmonic of the synchrotron frequency, a more appropriate technique to avoid those problems is the use of higher harmonic cavities, which have the important advantage of providing damping of the longitudinal modes without increasing the energy spread, i.e., without compromising the longitudinal emittance. In this work we present the design of a passive higher harmonic cavity system optimized for operation at the LNLS storage ring. The parameters for a set of cavities as well as the analysis of some of the effects that they may introduce in the beam dynamics are presented. An overview of the technical aspects related to the project, construction and installation of the cavities in the storage ring is also presented. | ||
| TUPCH130 | Development of the Feed-forward System for Beam Loading Compensation in the J-PARC RCS | 1319 |
|
||
| In the J-PARC Rapid Cycling Synchrotron (RCS), the heavy beam loading effects due to the high intensity proton beam must be compensated for stable acceleration. The beam feedforward technique is used to compensate the beam loading in the RCS. We present the development of the feedforward system. We designed and built the full-digital system with modern FPGAs to realize high accuracy, stability and predictability of the compensation. Because of the low Q value of each accelerating cavity, the wake voltage consists of not only the accelerating harmonic component but also higher harmonics. Thus, the system is designed to compensate the beam loading at several harmonics. The system has two parts. In the first part, vector components of the selected harmonic are detected from the beam signal picked up by a wall current monitor. The compensation RF signal is generated from the vector components with proper gain and phase in the latter part. The gain and phase are set individually for each harmonic and each cavity of the twelve cavities. We also present the preliminary test results of the newly developed modules. | ||
| TUPCH131 | High Power Test of MA Cavity for J-PARC RCS | 1322 |
|
||
| We have been constructing the RF system for the J-PARC RCS. Almost all of the power supplies and the tube amplifiers have been constructed, and the cavities are under construction. All of them are tested at the experimental hall before installing into the J-PARC RCS building. We test the hybrid cavity scheme to realize the optimum cavity Q-value. The results of the test are described. | ||
| TUPCH132 | Higher Order Mode (HOM) Damper of 500 MHz Damped Cavity for ASP Storage Ring | 1325 |
|
||
| TOSHIBA has delivered the storage ring RF system for the Australian Synchrotron Project(ASP). Two pairs of the 500MHz Higher Order Mode(HOM) damped cavities were applied for this system. Two on-centered and one off-centered dampers were attached for damping the longitudinal HOM impedance down to less than 20kOhm/GHz. In order to reduce the coupling of off-center damper for accelerating mode and improve cooling power of damper, New HOM damper was designed by optimizing SiC absorber structure and damper antenna length using HFSS code. The design and manufacture of the new HOM damper and the test are described. | ||
| TUPCH133 | Comparison of Measured and Calculated Coupling between a Waveguide and an RF Cavity Using CST Microwave Studio | 1328 |
|
||
| Accurate predications of RF coupling between an RF cavity and ports attached to it have been an important study subject for years for RF coupler and higher order modes (HOM) damping design. We report recent progress and a method on the RF coupling simulations between waveguide ports and RF cavities using CST Microwave Studio in time domain (Transit Solver). Comparisons of the measured and calculated couplings are presented. The simulated couplings and frequencies agree within ~ 10% and ~ 0.1% with the measurements, respectively. We have simulated couplings with external Qs ranging from ~ 100 to ~ 100, 000, and confirmed with measurements. The method should also work well for higher Qs, and can be easily applied in RF power coupler designs and HOM damping for normal-conducting and superconducting cavities. | ||
| TUPCH134 | RF Characteristics of the PEFP DTL | 1331 |
|
||
| A conventional 20 MeV Drift Tube Linac (DTL) for the Proton Engineering Frontier Project (PEFP) has been developed as a low energy section of a 100 MeV accelerator. The 20 MeV DTL consists of 4 tanks with 152 cells. The machine has a unique feature of driving the 4 tanks with a single klystron. Therefore it has several control knobs to compensate the errors of each tank during operation. To develop the RF control scheme, the variations of the RF parameters of each tank were measured under various environmental conditions such as wall temperature, cooling water temperature, and cooling water pressure. In addition, the behaviors of the RF parameters among the tanks were also monitored during high power operation. In this paper, the measurement results are discussed and the control scheme based on the results are proposed. | ||
| TUPCH135 | Characteristics of the PEFP 3 MeV RFQ | 1334 |
|
||
| A four-vane type 3 MeV, 350 MHz RFQ (Radiofrequency Quadrupole) has been developed as a front end part of PEFP (Proton Engineering Frontier Project) 100 MeV accelerator. After the completion of field tuning and high power conditioning at reduced duty, the initial operation of the RFQ with beam was carried out. During the initial test period, several parameters related with the RF and beam were measured to characterize the performance of the RFQ. Based on these measurements, several suggestions for further system improvement were proposed. In this paper, the initial test results are discussed and the suggestions for the system improvement are summarized. | ||
| TUPCH136 | Phase Measurement and Compensation System in PLS 2.5 GeV Linac for PAL-XFEL | 1337 |
|
||
| In PAL, We are preparing the 3.7 GeV PALXFEL project by upgrading the present 2.5GeV Linac. In present PLS Linac, the specifications of the beam energy spread and rf phase are 0.6%(peak) and 3.5 degrees(peak) respectively. And the output power of klystron is 80 MW at the pulse width of 4 ? and the repetition rate of 10 Hz. In XFEL, the specifications of the beam energy spread and rf phase are 0.03%(rms) and 0.01 degrees(rms) respectively. We developed an analogue and a digital phase measurement and rf phase compensation system for stable beam quality. This paper describes the microwave system for the PALXFEL and the rf phase measurement and phase compensation system. | ||
| TUPCH137 | Design of the RF System for 30 MeV Cyclotron | 1340 |
|
||
| LAD (Lab. of Accelerator Development) in KIRAMS (Korea Institute of Radiological & Medical Sciences) developed 13MeV medical cyclotron, named by KIRAMS-13, for PET (Positron Emission Tomography) in 2001. Now, KIRAMS-13 is widespread in Korea through the national project, "Development of Cyclotron and FDG Synthesis module." But, there is just one cyclotron for SPECT(Single Photon Emission Computed Tomography) in Korea, which is made by IBA, Belgium. If some problems are happened, we should shut off the cyclotron until IBA engineer fixes them. So, we decide to develop a 30MeV cyclotron, named KIRAMS-30, which has high-performance compared with existing commercial cyclotrons and will install this machine to radioactive isotopes production and researches in Advanced Radiation Technology Institute. In this paper, we design RF system, such as cavity, power coupler, and so on. At design of RF components, we consider mechanical stability, RF heating and cooling, arcing and multipacting, low maintenance. We simulate KIRAMS-30 with MWS (MicroWave Studio) and present simulation results. | ||
| TUPCH140 | Studies of Thermal Fatigue Caused by Pulsed RF Heating | 1343 |
|
||
| A future linear collider with a multi-TeV level of energies of the collided particles in the center of masses is naturally associated with high frequencies and a high power RF level. One of the interfering factors in this way is an effect of copper damage due to multi-pulse mechanical stress caused by high-power microwaves. In order to get new information about this effect, we started an experiment with the test cavity fed by 30 GHz FEM oscillator (15-30 MW, 100-200 ns, 0.5 - 1 Hz). Now we finished the second phase of this experiment where the test cavity was irradiated by 0.1 millions of RF pulses with temperature rise ~140 C in each pulse. The third phase is the experiment with 1 million pulses. In the next planned experiment with 36 GHz magnetron (0.1-0.15 MW, 1-2 mks, 0.01 - 1 kHz) we are going to investigate the thermal fatigue in most interesting for collider application region of temperatures (30-50 C). It is expected that these two experiments will supply necessary statistical information for the developed theory of the thermal fatigue in order to extrapolate lifetime numbers to other values of the temperature rise and pulse duration. | ||
| TUPCH141 | New Developments for the RF System of the ALBA Storage Ring | 1346 |
|
||
| ALBA is a 3 GeV, 400 mA, 3rd generation Synchrotron Light Source that is in the construction phase in Cerdanyola, Spain. The RF System will have to provide 3.6 MV of accelerating voltage and restore up to 540 kW of power to the electron beam. For that six RF plants, working at 500 MHz, are foreseen. The RF plants will include several new developments: 1) DAMPY cavity: the normal conducting HOM damped cavity developed by BESSY and based in the EU design; six will be installed. 2) CaCo: A cavity combiner to add the power to two 80 kW IOTs to produce the 160 kW needed for each cavity. 3) WATRAX: A waveguide transition to coaxial, specially designed to feed the DAMPY cavities due to the geometrical and cooling constrains. 4) IQ LLRF: The low level RF will be based on the IQ modulation/demodulation technique, both analogue and digital approach are being pursued. This paper describes the Storage Ring RF System and reports about the status of these new developments. | ||
| TUPCH142 | Development of a Novel RF Waveguide Vacuum Valve | 1349 |
|
||
| The development of a novel rf waveguide vacuum valve is presented. The rf design is based on the use of TE0n modes of circular waveguides. In the device, the T·1001 mode at the input is converted into a mixture of several TE0n modes which provide low-loss rf power transmission across the vacuum valve gap, these modes are then converted back into the T·1001 mode at the output. There are a number of advantages associated with the absence of surface fields in the region of the valve: 1)Possibility to use commercially available vacuum valves equipped with two specially designed mode converter sections. 2)No necessity for an rf contact between these two sections. 3)Increased potential for high power rf transmission. This technology can be used for all frequencies for which vacuum waveguides are used. The only drawback is that, in rectangular waveguides, mode converters from the operating mode into the T·1001 mode and back again are necessary. Experimental results for the 30 GHz valves developed for the CLIC Test Facility 3 (CTF3) are presented showing in particular that the rf power transmission losses are below 1%. | ||
| TUPCH143 | High Gradient Tests of an 88 MHZ RF Cavity for Muon Cooling | 1352 |
|
||
| The scheme for a Muon Cooling channel developed at CERN in the frame of Neutrino Factory studies foresees the use of 44 and 88 MHz cavities operating at a real-estate gradient as high as 4 MV/m. To assess the feasibility of this scheme, including high-gradient operation at relatively low frequency and the production and handling of high RF peak powers, a test stand was assembled at CERN. It included an 88 MHz resonator reconstructed from a 114 MHz cavity previously used for lepton acceleration in the PS, a 2.5 MW final amplifier made out of an old linac unit improved and down-scaled in frequency, and a PS spare amplifier used as driver stage. After only 160 hours of conditioning the cavity passed the 4 MV/m level, with local peak surface field in the gap exceeding 25 MV/m (2.4 times the Kilpatrick limit). The gradient was limited by the amplifier power, the maximum RF peak output power achieved during the tests being 2.65 MW. This paper presents the results of the tests, including an analysis of field emission from the test cavity, and compares the results with the experience in conditioning ion linac RF cavities at CERN. | ||
| TUPCH144 | Automatic Conditioning of the CTF3 RF System | 1355 |
|
||
| The RF system of CTF3 (CLIC Test Facility 3) includes ten 35 MW to 40 MW 3 GHz klystrons and one 20 MW 1.5 GHz klystron. High power RF conditioning of the waveguide network and cavities connected to each klystron can be extremely time consuming. Because of this, a fully automatic conditioning system has been developed within a CERN JINR (Dubna) collaboration. It involves relatively minor hardware additions, most of the work being in application and front-end software. The system has already been used very successfully. | ||
| TUPCH145 | The MUCOOL RF Program | 1358 |
|
||
| Efficient muon cooling requires high RF gradients in the presence of high (~3T) solenoidal fields. The Muon Ionization Cooling Experiment (MICE) also requires that the x-ray production from these cavities is low, in order to minimize backgrounds in the particle detectors that must be located near the cavities. These cavities require thin Be windows to ensure the highest fields on the beam axis. In order to develop these cavities, the MUCOOL RF Program was started about 6 years ago. Initial measurements were made on a six-cell cavity and a single-cell pillbox, both operating at 805 MHz. We have now begun measurements of a 201 MHz pillbox cavity. This program has led to new techniques to look at dark currents, a new model for breakdown and a general model of cavity performance based on surface damage. The experimental program includes studies of thin Be windows, conditioning, dark current production from different materials, magnetic-field effects and breakdown. We will present results from measurements at both 805 and 201 MHz. | ||
| TUPCH146 | The Interactions of Surface Damage on RF Cavity Operation | 1361 |
|
||
| Studies of low frequency RF systems for muon cooling has led to a variety of new techniques for looking at dark currents, a new model of breakdown, and, ultimately, a model of RF cavity operation based on surface damage. We find that cavity behavior is strongly influenced by the spectrum of enhancement factors on field emission sites. Three different spectra are involved: one defining the initial state of the cavity, the second determined by the breakdown events, and the third defining the equilibrium produced as a cavity operates at its maximum field. We have been able to measure these functions and use them to derive a wide variety of cavity parameters: conditioning behavior, material, pulse length, temperature, vacuum, magnetic field, pressure, gas dependence. In addition we can calculate the dependence of breakdown rate on surface field and pulse length. This work correlates with data from Atom Probe Tomography. We will describe this model and new experimental data. | ||
| TUPCH147 | High Pressure RF Cavities in Magnetic Fields | 1364 |
|
||
| A study of RF breakdown in pressurized cavities immersed in strong magnetic fields has begun as part of a program to develop RF cavities filled with dense hydrogen gas to be used for muon ionization cooling. A pressurized 805 MHz test cell is being used at Fermilab to compare the conditioning and breakdown behavior of copper, molybdenum, and beryllium electrodes as functions of hydrogen and helium gas densities and magnetic field strength. These results will be compared to the predicted or known RF breakdown behavior of these metals in vacuum with and without external magnetic fields. | ||
| TUPCH148 | 201 MHz Cavity R&D for MUCOOL and MICE | 1367 |
|
||
| We describe the design, fabrication and preliminary testing of the prototype 201 MHz copper cavity for a muon ionization cooling channel. Application of the cavity includes the Muon Ionization Cooling Experiment (MICE) as well as cooling channels for a neutrino factory or a muon collider. This cavity was developed by the US MUCOOL collaboration and is being tested in the MUCOOL Test Area (MTA) at Fermilab. In order to achieve a high accelerating gradient, the cavity beam irises are terminated by a pair of curved, thin beryllium windows. Several of the fabrication methods developed for this cavity and the windows are novel and offer significant cost savings compared to conventional construction methods. Cavity thermal and RF performance will be compared to FEA modeling predictions. RF commissioning results will be presented. | ||
| TUPCH149 | Design of a 10 MHz Heavy Ion RFQ for a RIA Post Accelerator | 1370 |
|
||
| Design of a 10 MHz heavy ion RFQ for the RIA post accelerator is described. Main rf and mechanical parameters of the proposed accelerator are given. This 10 MHz RFQ is capable of accelerating beams from an initial energy of 2 keV/u to 8 keV/u covering a charge to mass ratio from 1/10 to 1/240. | ||
| TUPCH150 | Improved 1.3 GHz Inductive Output Tube for Particle Accelerators | 1373 |
|
||
| There is an increasing requirement for RF power sources in the L-band frequency range for operation in particle accelerators. Previously (at PAC 2005), the design, development and initial testing of a new L-band 16kW cw inductive output tube (IOT) was described. This paper discusses the detailed performance characteristics of the latest EEV IOT116LS embodying the most recent design improvements and presents data demonstrating its suitability for operation at 1.3GHz in the next generation of light sources. | ||
| TUPCH151 | ERLP/4GLS Low Level Radio Frequency System | 1376 |
|
||
| The Energy Recovery Linac Prototype (ERLP) being constructed at Daresbury Laboratory will use an analog-based low level RF (LLRF) control system designed and built at FZR Rossendorf. Once the machine is operational, the testing and development of a digital LLRF feedback system will take place using the ERLP as a testbed. | ||
| TUPCH152 | MICE RF Test Stand | 1379 |
|
||
| The Muon Ionization Cooling Experiment (MICE) RF test stand is being assembled at Daresbury Laboratory. This will provide a test bed for power amplifiers to produce the 2MW 200MHz RF for the MICE experiment RF cavities. Initial design and proposed layout of the RF system are described. | ||
| TUPCH153 | IOT Testing at the ERLP | 1382 |
|
||
| The testing of Inductive Output Tubes (IOT) at 1.3GHz is underway for use on the Energy Recovery Linac Prototype (ERLP) being constructed at Daresbury Laboratory. A 50KV high voltage power supply (HVPS) has been commissioned and characterised for use as a test RF supply. This will be used to power the ERLP RF system in both continuous and pulse modes of operation. First results are presented of the IOTs and the use of the HVPS system. | ||
| TUPCH154 | RF Amplifier for Next Generation Light Sources | 1385 |
|
||
| This paper describes the design concepts and development issues around generating a compact 16kW 1.3GHz RF amplifier for use in the next generation of light sources. These amplifiers need to be operated for extended periods to maximise use of the facility and so high reliability and availability are of key importance. Equally important are the capabilities to have extensive self-monitoring and fault prediction, autonomous operation, low heat dissipation to air, and easy maintenance. The design and development of such an RF amplifier based on the latest e2v technologies 1.3GHz inductive output tube (IOT) will be described. The RF amplifier equipment makes extensive use of commercially available products and industry collaborations to produce an amplifier that meets all the requirements yet can be manufactured and operated in a most cost effective manner. Prototype equipment will be shown at EPAC 06. | ||
| TUPCH155 | 2D and 1D Surface Photonic Band Gap Structures for Accelerator Applications | 1388 |
|
||
| High frequency (26.5GHz to 40GHz), high power (tens of MW) microwave sources are required for cavity testing and conditioning applications in accelerators such as CLIC. The first study of microwave radiation from a co-axial Free-Electron Maser (FEM) based on a two-mirror cavity formed by a 2D Surface Photonic Band Gap (SPBG) structure (input mirror 10.4cm) and 1D SPBG structure (output mirror 10cm) is presented. The electron beam source consisted of a magnetically insulated plasma flare emission carbon cathode. Application of a 450kV voltage pulse of duration ~250ns across the cathode and grounded anode resulted in the production of a 7.0cm diameter annular electron beam of current ~1500A. The output radiation power from the FEM was measured using a Ka-band horn with 60dB of attenuation in front of a microwave detector located at a distance of 1.5m from the output window. By integrating the microwave power measured at the detector over the radiation pattern a total power of 50 (±10) MW corresponding to an efficiency of ~9% was calculated. The location of the operating frequency was found to lie between 35GHz and 39GHz, which agrees with theoretically predicted frequency of 37.2GHz. | ||
| TUPCH156 | Design and Simulation of a Cusp Gun for Gyro-amplifier Application in High Frequency RF Accelerators | 1391 |
|
||
| Gyro-amplifiers have potential as the high frequency RF drivers for particle accelerators. They require relativistic electron beams with low velocity spread and with a high fraction of the electron energy associated with the cyclotron motion. For harmonic operation and mode control an axis-encircling beam is desirable. The passage of an electron beam through a non-adiabatic magnetic field reversal (cusp) converts part of the electron beam's axial velocity into axis-encircling transverse velocity. A cusp-based electron beam forming system, yielding a 10MW, 150kV, 70A axis-encircling beam will be presented. This cusp gun is being designed as the electron beam source for a microwave gyro-amplifier that is relevant for high frequency accelerator applications. The latest results from numerical simulations and experiments will be presented and compared. | ||
| TUPCH158 | High Power, Solid State RF Amplifiers Development for the EURISOL Proton Driver | 1394 |
|
||
| A 5 kW solid-state RF amplifier for the SPES and EURISOL projects has been built and extensively tested. High reliability and low cost are the main goals for this device, an evolution of a 2.5 kW unit previously developed and presented at EPAC 02. The description of the amplifier, especially designed for superconducting cavities, its characteristics and test results will be illustrated and discussed, as well as the design and construction of two new 10 kW amplifier units that have recently started. | ||
| TUPCH159 | High Power Waveguide Switching System for SPring-8 Linac | 1397 |
|
||
| A vacuum waveguide switch has been developed to build a backup system of an RF source for the electron injector system and the klystron drive line in the SPring-8 linac. A high power test of the waveguide switch was carried out, and the maximum RF power of 62 MW in peak, 1μsecond in pulse width and 10 pps in repetition rate was achieved without serious problems in RF and vacuum characteristics. The backup system utilizing this waveguide switch has been installed in the electron injector system. | ||
| TUPCH160 | Novel Conception of Beam Temperature in Accelerator and Applications | 1400 |
|
||
| In this paper, we will introduce a novel conception of beam temperature in accelerator, discuss the calculation method. And finally the author will show an example on the beam temperature in a klystron. | ||
| TUPCH162 | Operation Results of 1 MW RF Systems for the PEFP 20 MeV Linac | 1402 |
|
||
| The PEFP 20 MeV linear accelerator is composed of a 3 MeV RFQ and 20 MeV DTL. Two sets of 1MW, 350MHz RF systems drive the RFQ and DTL. The RF system can perform a 100% duty operation. The TH2089F klystron is used as an RF source. During the test operation, only the driving RF signal of the klystron was operated in pulse mode, while the electron beam was maintained in DC mode. The klystron power supplies and cooling systems were also operated in 100% duty mode. In this paper, the operation results of 1 MW RF systems including klystron power supply and cooling system are discussed and propose possible options to improve the operation conditions based on the results. | ||
| TUPCH163 | Status of 30 GHz High Power RF Pulse Compressor for CTF3 | 1405 |
|
||
| A 70 ns 30 GHz pulse compressor with resonant delay lines has been built and installed in the CTF3 test area to obtain the high peak power of 150 MW necessary to demonstrate the full performance of the new CLIC accelerating structure. This pulse compressor will be commissioned at high power in 2006. Different methods to provide fast RF phase switching are discussed. The current status of the CTF3 RF pulse compressor commissioning and first results are presented. | ||
| TUPCH164 | Ka-band Test Facility for High-gradient Accelerator R&D | 1408 |
|
||
| Achievement of high acceleration gradients in room-temperature structures requires basic studies of electric and magnetic RF field limits at surfaces of conductors and dielectrics. Facilities for such studies at 11.4 GHz have been in use at KEK and SLAC; facilities for studies at 17.1 GHz are being developed at MIT and UMd; and studies at 30 GHz are being conducted at CERN using the CLIC drive beam to generate short intense RF pulses. Longer pulse studies at 34 GHz are to be carried out at a new test facility being established at the Yale Beam Physics Laboratory, built around the Yale/Omega-P 34-GHz magnicon. This high-power amplifier, together with an available ensemble of components, should enable tests to be carried at up to about 9 MW in 1 mcs wide pulses at up to four output stations or, using a power combiner, at up to about 35 MW in 1 mcs wide pulses at a single station. RF pulse compression is planned to be used to produce 100-200 MW, 100 ns pulses; or GW-level, 1 mcs wide pulses in a resonant ring. A number of experiments have been prepared to utilize multi-MW 34-GHz power for accelerator R&D, and users for future experiments are encouraged to express their interest. | ||
| TUPCH165 | Compact Single-channel Ka-band SLED-II Pulse Compressor | 1411 |
|
||
| Basic studies of factors that limit RF fields in warm accelerator structures require experiments at RF power levels that can only be produced from an intense drive beam, as with CLIC studies, or using pulse compression of output pulses from the RF source. This latter approach is being implemented to compress output pulses from the Yale/Omega-P 34-GHz magnicon to produce ~100-200 MW, 100 ns pulses. A new approach for passive pulse compression is described that uses a SLED-II-type circuit operating with axisymmetrical modes of the TE0n type that requires only a single channel instead of the usual double channel scheme. This allows avoidance of a 3-dB coupler and need for simultaneous fine tuning of two channels. Calculations show that with this device at 34 GHz one can anticipate a power gain of 3.3:1, and an efficiency of 66% for a 100 ns wide output pulse, taking into account losses and a realistic 50-ns long 180 degrees phase flip. | ||
| TUPCH166 | Multi-megawatt Harmonic Multiplier for Testing High-gradient Accelerator Structures | 1414 |
|
||
| Basic studies for determining the RF electric and magnetic field limits on surfaces of materials suitable for accelerator structures for a future multi-TeV collider, and for the testing of the accelerator structures and components themselves, require stand-alone high-power RF sources at several frequencies, from 10 to 45 GHz. A relatively simple and inexpensive two-cavity harmonic multiplier at 22.8, 34.3, or 45.7 GHz is suggested to be the stand-alone multi-MW RF power source for this application. The design is based on the use of an existing SLAC electron gun, such as the XP3 gun, plus a beam collector as used on the XP3 klystron. RF drive power would be supplied from an 11.4 GHz, 50 or 75 MW SLAC klystron and modulator, and a second modulator would be used to power the gun in the multiplier. Preliminary computations show that 64, 55, and 47 MW, respectively, can be realized in 2nd, 3rd, and 4th harmonic multipliers at 22.8, 34.3, and 45.7 GHz using 75 MW of X-band drive power. | ||
| TUPCH167 | Modeling and Simulation Results of High-power HOM IOTs | 0 |
|
||
| The inductive output tube (IOT) continues to be the device-of-choice for terrestrial UHF broadcast applications due to its high efficiency, linearity, compactness, etc.; the same reasons that make this an attractive choice for scientific users. The IOT is being considered for a growing number of accelerator programs requiring multi-kilowatts of continuous wave power, at UHF and L-band frequencies. A number of vacuum electron device manufacturers are developing IOTs in support of these programs. There are an equal number of accelerator programs that operate pulsed, requiring high peak powers, where the only sources available are klystrons and MBKs. For these applications a higher-order mode IOT (HOM IOT) shows great promise for the same reasons described above. Modeling and simulation results for devices built to operate within the UHF and L-band frequency ranges will be shown, at power levels up to 5 MW. | ||
| TUPCH168 | IOTs: The Next Generation RF Power Sources for Accelerators | 0 |
|
||
| A new generation of Inductive Output Tubes (IOT) have been developed with a focus on cost reduction, robustness, stability, enhanced power, improved gain and efficiency. As demonstrated with our L-band integral cavity IOT, a new family of IOTs can operate as CW or pulse amplifiers with up to 80 kW CW and 120 kW peak output power. Switching between the CW and pulse mode is easy and simple. In this paper, we will present our new compact designs and the latest performance data. | ||
| TUPCH171 | Calculation, Measurement and Analysis of Vacuum Pressure Data and Related Bremsstrahlung Levels on Straight Sections of the ESRF | 1417 |
|
||
| One of the major personal safety issues of modern synchrotron radiation (SR) light sources is the minimization of the exposure of beamline staff and users to high-energy bremsstrahlung (BS) radiation generated in the straight sections of the storage ring and entering the optics hutches of the beamlines. This is particularly important when insertion device (ID) narrow-gap chambers are installed, nowadays characterized by very low specific conductances. At the ESRF, this has led to the implementation of systematic measurements of BS levels and vacuum conditioning curves, in conjunction with the installation of non-evaporable getter (NEG)-coated ID chambers. A dedicated beamline is used to do on-axis measurements of the BS intensity during the initial conditioning period of newly installed NEG-coated ID chambers. This paper will show results of measurements and calculations performed throughout the years, and comment on the suitability from the radiation safety point of view of the installation of NEG-coated chambers in large numbers around the ring. | ||
| TUPCH172 | Status Report on the Performance of NEG-coated Chambers at the ESRF | 1420 |
|
||
| At the ESRF, the use of NEG-coated narrow gap chambers for insertion device (ID) straight sections has become the standard choice for in-air IDs. A total of 25 chambers have been installed at different times in the ring, with 19 being installed as of Jan 2006, for a total length of 82 m. The vacuum performance has been excellent for all but one of them. It has been found that the now standard "10mm" design, i.e. a 5 m-long, 57x8 mm2 ellipse, is compatible with the multi-bunch operation at 200 mA. Runs at higher currents, performed in preparation of current upgrades, have gone smoothly. During 2005, a 3.5 m-long prototype of a chamber suited for installation in the achromat part of the lattice has been installed in the ring. It was characterized by a much smaller cross-section (30x20 mm2, HxV) as compared to a standard chamber (74x33 mm2, HxV), and by the absence of three lumped pumps, replaced by the NEG-coating. The data taken during a full run have been extremely encouraging, to the point of considering the adoption of a similar design for a future upgrade of the storage ring lattice and vacuum system. A status report will be given, alongside with a discussion of future plans. | ||
| TUPCH173 | Understanding of Ion Induced Desorption Using the ERDA Technique | 1423 |
|
||
| In heavy ion synchrotrons like SIS18 at GSI high energetic ions can impact on the beam pipe and release gas molecules. This so called "ion induced desorption" deteriorates the accelerator vacuum and as a consequence the beam life time and luminosity. To minimize the pressure increase it is necessary to understand the physics of ion induced desorption. The elastic recoil ion detection analysis (ERDA) can give a time resolved element specific depth profile of a probe under ion bombardment. A UHV-ERDA setup has been installed at GSI to investigate correlations between desorption and material properties as well as its dose dependant evolution. Recent experiments have shown the influence of the surface state of a sample such as the oxide layer on steel as well as the importance of a high-purity bulk such as in silicon and OFHC copper. We will present the results of gold coated copper in comparison to stainless steel as applicable materials for accelerators. | ||
| TUPCH174 | Vacuum Issues and Challenges of SIS18 Upgrade at GSI | 1426 |
|
||
| For the present experiment programm and for the planned FAIR facility the heavy ion synchroton SIS18 at GSI has to reach the space charge limit for highly and intermediate charged heavy ions. For the booster mode of SIS18 the number of 1x1012 ions per second in 4 Hz operation mode is specified. To achive this requirement a dynamic vacuum in the 10-12 mbar region has to be garanteed. The poster will present the status of recent R & D work concerning the SIS18 vacuum upgrade, with a focus on the new GSI NEG coating facility and on ion-induced desorption measurements using advanced ion beam analysis. | ||
| TUPCH175 | The Vacuum System of FAIR Accelerator Facility | 1429 |
|
||
| The FAIR accelerator complex consists of two superconducting synchrotrons (SIS100 and SIS300) with a circumference of 1083.6m each, a high energy beam transport system (HEBT) with a total length of about 2.5km and four storage rings (CR, RESR, HESR and NESR). Their length varies between 200m and 550m. For each of the subsystems, different vacuum requirements have to be fulfilled. The vacuum system of SIS100 and SIS300 consists of cryogenic and bakeable room temperature sections, where a pressure in the lower 10-12 mbar range is needed. For HEBT, also a combination of cryogenic and room temperature sections, a vacuum pressure of 10-9 mbar is sufficient. The storage rings will be operated in a pressure range from 10-9 mbar to 10-12 mbar. In the poster a detailed layout of the vacuum systems and technical solutions will be presented. | ||
| TUPCH177 | Measurement of the Sorption Characteristics of NEG Coated Pipes: The Transmission Factor Method | 1432 |
|
||
| ZrTiV Non Evaporable Getter (NEG) coatings of vacuum chambers have found application in the particle accelerators to lower the gas pressure, during the operative conditions. For that, the characterization of the actual pumping speed of the NEG coating is a key issue. It is carried out by means of the dynamic sorption method according to ASTM F798-82 standard, conducted "offline" on a sample (coupon), suitably positioned inside the chamber to be coated and recovered after the process. To evaluate in-situ the sorption characteristics of getter coated chambers, a different measurement technique (Trasmission Factor Method) is here described. It is based on the measurement of pressures ratio at the inlet and the outlet of a coated pipe, under a flow of test gas. A calibration curve permits to evaluate sticking probability of the coated surface from the pressure ratio. The use of reference samples to calibrate the method is quite difficult. A better approach is a modellistic one, finding the dependency of pressure ratio on the average sticking probability, the pipe length and the section geometry and dimensions. Preliminary experimental results will be shown. | ||
| TUPCH178 | Deposition of Non Evaporable Getter (NEG) Films on Vacuum Chambers for High Energy Machines and Synchrotron Radiation Sources | 1435 |
|
||
| Non Evaporable Getter (NEG) films, sputter deposited onto the internal surfaces of vacuum chambers reduce thermal out-gassing and provide conductance-free distributed pumping ability, allowing the achievement of very low pressure inside narrow and conductance limited chambers, like Insertion Devices. NEG films do show additional interesting features, like low secondary electron yield and low gas de-sorption rates under ions, electrons and photons bombardment. They seem therefore ideal to reduce electron multi-pacting and dynamic gas de-sorption induced beam instabilities in high energy machines. This paper presents SAES getters experience in the NEG coating of chambers of different geometries and sizes for a variety of projects related to high energy machines and synchrotron radiation facilities. Examples of applications, as well as most common issues related to chambers preparation, film deposition, characterization and quality control, are given. Areas where further work is still necessary to fully take advantage of NEG film properties will be also discussed. | ||
| TUPCH179 | R&D on Copper Beam Ducts with Antechambers and Related Vacuum Components | 1438 |
|
||
| A beam duct with antechambers is able to reduce the effect of photoelectrons and, as a result, to suppress the electron cloud effect of positron or proton beam. It will be adopted for a future high current positron/proton rings and also a damping ring of a linear collider. Copper beam ducts with one or two antechambers were manufactured for test and the feasibility was studied. The test chambers were then installed into the KEK B-factory positron ring and the performance was investigated with a beam current up to 2000 mA. The temperature, the pressure and the electron density in the beam channel were measured during the beam operation. The photoelectron, for example, was found to be well suppressed as expected compared to that of a simple circular beam duct. The related vacuum components, such as a connection flange, a bellows chamber and a gate valve with the same cross section to the beam duct, were also developed and tested together with the beam duct. | ||
| TUPCH182 | Radiation Monitors as a Vacuum Diagnostic in the Room Temperature Parts of the LHC Straight Sections | 1441 |
|
||
| In the absence of collisions, inelastic interactions between protons and residual gas molecules are the main source of radiation in the room temperature parts of the LHC long straight sections. In this case the variations in the radiation levels will reflect the dynamics of the residual pressure distribution. Based on the background simulations for the long straight section of the LHC IP5 and on the current understanding of the residual pressure dynamics, we evaluate the possibility to use the radiation monitors for the purpose of the vacuum diagnostic, and we present the first estimates of the predicted monitor counts for different scenarios of the machine operation. | ||
| TUPCH183 | H2 Equilibrium Pressure in a NEG-coated Vacuum Chamber as a Function of Temperature and H2 Concentration | 1444 |
|
||
| Non Evaporable Getter (NEG) coating is used in the LHC room- temperature sections to ensure a low residual gas pressure for its properties of distributed pumping, low outgassing and desorption under particle bombardment; and to limit or cure electron cloud build-up due to its low secondary electron emission. In certain regions of the LHC, and in particular close to the beam collimators, the temperature of the vacuum chamber is expected to rise due to energy deposition from particle losses. Gas molecules are pumped by the NEG via dissociation on the surface, sorption at the superficial sites and diffusion into the NEG bulk. In the case of hydrogen, the sorption is thermally reversible, causing the residual pressure to increase with NEG temperature and amount of H2 pumped. Measurements were carried out on a stainless steel chamber coated with TiZrV NEG as a function of the H2 concentration and the chamber temperature, to estimate the residual gas pressure in the collimator regions for various LHC operation scenarios, corresponding to different particle loss rates and times between NEG regenerations. The results are presented in this paper and discussed. | ||
| TUPCH186 | Low Level RF System Development for SOLEIL | 1447 |
|
||
| The Low Level RF system that is used in the SOLEIL storage ring consists in fully analog "slow" amplitude, phase and frequency loops, complemented with a direct RF feedback. A fast digital FPGA-based I/Q feedback, currently under development, will be implemented later on. The performance of both systems has been evaluated using a Matlab-Simulink-based simulation tool. The computed and first experimental results are reported. | ||
| TUPCH187 | DSP-based Low Level RF Control as an Integrated Part of DOOCS Control System | 1450 |
|
||
| The Distributed Object Oriented Control System (DOOCS) has been developed at DESY as a control system for TTF/VUV-FEL. The DSP based low level RF control system is one of the main subsystems of the linac. Several DOOCS device servers and client applications have been developed to integrate low level RF control into the TTF/VUV-FEL control system. The DOOCS approach defines each hardware device as a separate object and this object is represented in a network by a device server, which handles all device functions. A client application can have access to the server data using the DOOCS application programming interface. A set of generic and specially devoted programs provide the tools for the operators to control the RF system. The RF operation at the linac is being automated by the implementation of DOOCS finite state machine servers. | ||
| TUPCH188 | Phase Stability of the Next Generation RF Field Control for VUV- and X-ray Free Electron Laser | 1453 |
|
||
| For pump and probe experiments at VUV- and X-ray free electron lasers the stability of the electron beam and timing reference must be guaranteed in phase for the injector and bunch compression section within a resolution of 0.01 degree (rms) and in amplitude within 1 10-4 (rms). The performance of the field detection and regulation of the acceleration RF directly influences the phase and amplitude stability. In this paper we present the phase noise budget for a RF-regulation system including the noise characterization of all subcomponents, in detail down-converter, ADC sampling, vector-modulator, master oscillator and klystron. We study the amplitude to phase noise conversion for a detuned cavity. In addition we investigate the beam jitter induced by these noise sources within the regulation and determine the optimal controller gain. We acknowledge financial support by DESY Hamburg and the EUROFEL project. | ||
| TUPCH189 | FPGA-based RF Field Control at the Photocathode RF Gun of the DESY VUV-FEL | 1456 |
|
||
| At the DESY Vacuum Ultraviolet Free Electron Laser (VUV-FEL) bunch peak current and the SASE effect are (amongst other parameters) sensitive to beam energy and beam phase variations. The electron bunches are created in an rf gun, which does not have field probes. Variations of the gun rf field cause beam energy and phase variations. They have a significant influence on the overall performance of the facility. DSP based rf field control used previously was only able to stabilize the rf output of the klystron. This was due to the lack of processing power and the over-all loop delay. The controller was not able to provide satisfactory rf field stability in the gun. Replacing the DSP hardware by the new FPGA-based hardware Simulation Controller (SimCon), we are able to reduce the latency within the digital part significantly allowing for higher loop gain. Furthermore SimCon provides sufficient processing power for calculating a probe signal from the forward and reflected power as input for PI and adaptive feed forward (AFF) control. In this paper we describe the algorithms implemented and the gun rf field stability obtained. | ||
| TUPCH190 | Universal Controller for Digital RF Control | 1459 |
|
||
| Digital RF control systems allow to change the type of controller by programming of the algorithms executed in FPGAs and/or DSPs. It is even possible to design a universal controller where the controller mode is selected by change of parameters. The concept of a universal controller includes the self-excited-loop (SEL) and generator driven resonator (GDR) concept, the choice of I/Q and amplitude or phase control, and allows for different filters (including Kalman filter and method of optimal controller synthesis) to be applied. Even time-varying mixtures of these modes are possible. Presented is the implementation of such a controller and the operational results with a superconducting cavity. | ||
| TUPCH191 | Considerations for the Choice of the Intermediate Frequency and Sampling Rate for Digital RF Control | 1462 |
|
||
| Modern FPGA-based rf control systems employ digital field detectors where an intermediate frequency (IF) in the range of 10 to more than 100 MHz is sampled with a synchronized clock. Present ADC technology with 14-16 bit resolution allows for maximum sampling rates up to 250 MHz. While higher IF's increase the sensitivity to clock jitter, lower IF frequencies are more susceptible to electromagnetic noise. The choice of intermediate frequency and sampling rate should minimize the overall detector noise, provide high measurement bandwidth and low latency in field detection, and support algorithms for optimal field estimation. | ||
| TUPCH193 | Low Level RF Control System Modules for J-PARC RCS | 1465 |
|
||
| After completing the design phase, the VME modules for the Low Level RF Control (LLRF) of the Rapid Cycling Synchrotron of J-PARC are now in the production and debugging phase. First all modules are tested for basic functionality, for example dual harmonic signal generation. Then sets of modules are connected together to check higher-level functions and feedback. Finally, the LLRF modules are interfaced to high voltage components like amplifiers and cavities. We present the results of these tests, the test methods and test functions on several levels. This way we simulate beam operation working conditions and gain experience in controlling all parameters. | ||
| TUPCH194 | Analogue and Digital Low Level RF for the ALBA Synchrotron | 1468 |
|
||
| ALBA is a 3 GeV, 400 mA, 3rd generation Synchrotron Light Source that is in the construction phase in Cerdanyola, Spain. The RF System will have to provide 3.6 MV of accelerating voltage and restore up to 540 kW of power to the electron beam. Two LLRF prototypes are being developed in parallel, both following the IQ modulation/demodulation technique. One is fully based on analogue technologies; the other is based on digital FPGA processing. The advantages of the IQ technique will be summarised and the control loop logic described. The hardware implementation in analogue as well as in digital format will be presented and first test results shown. The implementation of the same logic with both technologies will give us a perfect bench to compare, and use the better of them, for the final LLRF of the ALBA synchrotron. | ||
| TUPCH195 | The LHC Low Level RF | 1471 |
|
||
| The LHC RF consists in eight 400 MHz superconducting cavities per ring, with each cavity independently powered by a 300 kW klystron, via a circulator. The challenge for the Low Level is to cope with both very high beam current (more than 1A RF component) and excellent beam lifetime (emittance growth time in excess of 25 hours). For each cavity we have a Cavity Controller rack with two VME crates implementing a strong RF Feedback, a Tuner Loop with a new algorithm, a Klystron Ripple Loop and a Conditioning system. In addition each ring has a Beam Control system (four VME crates) including Frequency Program, Phase Loop, Radial Loop and Synchronization Loop. A Longitudinal Damper (dipole and quadrupole mode) acting via the 400 MHz cavities is included to reduce emittance blow-up due to filamentation following phase and energy errors at injection. Finally an RF Synchronization system implements the bunch into bucket transfer from the SPS into each LHC ring. When fully installed in 2007 the whole system will count over three hundreds home-designed VME cards of twenty-three different models installed in fourty-five VME crates. | ||
| TUPCH196 | Digital Design of the LHC Low Level RF: the Tuning System for the Superconducting Cavities | 1474 |
|
||
| The low level RF systems for the LHC are based extensively on digital technology, not only to achieve the required performance and stability but also to provide full remote control and diagnostics facilities needed in a machine where most of the RF system is inaccessible during operation. The hardware is based on modular VME but with additional low noise linear power supplies and a specially designed P2 backplane for timing distribution and fast data interchange. Extensive design re-use and the use of graphic FPGA design tools have streamlined the design process. A milestone was the test of the tuning system for the superconducting cavities. The tuning control module is based on a 2M gate FPGA with on-board DSP. Its design and functionality are described, including features such as automatic measurements of cavity characteristics and transient response of the tuning system. The tuner control is used as a test bed for LHC standard software components. A full 'vertical slice' from remote application down to the hardware has been tested. Work is ongoing on the completion of other modules and building up the software and diagnostics facilities needed for RF system commissioning. | ||
| TUPCH197 | Low level RF System Development for the Superconducting Cavity in NSRRC | 1477 |
|
||
| The present low level system in NSRRC is based on analogy feedback control scheme. It provides feedback regulation on EM field, phase, and resonant frequency of the superconducting RF cavity. In order to address the required flexibility and improve diagnostic of the RF control system, a new digital low-level RF system based on Field Programmable Gate Array (FPGA) is proposed to be develop in house. The status of current analogy low level RF system and the specification of new digital FPGA based low level RF system are reposted herein. | ||
| TUPCH200 | Amplitude Linearizers for PEP-II 1.2 MW Klystrons and LLRF Systems | 1480 |
|
||
| The PEP-II B-factory has aggressive current increases planned for luminosity through 2008. At 2.2 A (HER) on 4 A (LER) currents, longitudinal growth rates will exceed the damping rates achievable in the existing low level RF and longitudinal low mode feedback systems. Klystron gain non-linearity has been shown to be a key contributor to these increased growth rates through time domain non-linear modeling and machine measurements. Four prototype klystron amplitude modulation linearizers have been developed to explore improved linearity in the LLRF system. The linearizers operate at 475 MHz with 15 dB dynamic range and 1 MHz linear control bandwidth. Results from lab measurements and high current beam tests are presented. Future development progress and production designs are detailed. |