| Paper | Title | Page |
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| THPP001 | Development of FFAG Electron Accelerator | 3372 |
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| Electron Beam (EB) Accelerators have been used in the many industrial fields to improve physical properties of the material. Examples are wire and cable industries, rubber tire industries, foam industries, etc. EB is also widely used for medical device sterilization as a popular tool. High power, high reliability, compactness and low cost are key requirements to get popularity of the technology and to open up its application fields. The paper will present FFAG electron accelerator to meet these requirements that NHV Corporation recently developed and some of the interesting performance such as beam extraction efficiency will be discussed in the paper. | ||
| THPP002 | EMMA RF Cavity Design and Prototype Testing at Daresbury | 3374 |
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At PAC’07 we discussed the design of a prototype cavity to be used on EMMA*. EMMA is a prototype non-scalling FFAG. It will contain 19 RF cavities operating at 1.3 GHz with a baseline accelerating voltage of 120 kV. A prototype cavity has been manufactured by Niowave, Inc. and we will present a discussion of its RF and mechanical design. This cavity was put through low power tests, to determine frequency, tuning range, shunt impedance and Q of the cavity; and high power tests, to confirm power handling ability, when it arrived at Daresbury Laboratory this spring. The results of these tests were compared to the simulations and a bead pull was carried out to obtain the field profile. The cavities for EMMA are likely to be powered by IOTs, these will be used for the high power tests, which will demonstrate cavity operation to the required maximum of 180 kV.
*E. Wooldridge et al. "RF Cavity Development for FFAG Application on ERLP at Daresbury," Proceedings of PAC’07, Albuquerque, NM (2007). |
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| THPP003 | RF System Design for the EMMA FFAG | 3377 |
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| In this report the RF system design for EMMA is described. The power source options, power supplies, waveguide distribution scheme and control system is discussed. The architecture necessary to meet the operation specifications requires a large degree of adjustment. To simplify commissioning and enhance the versatility of the machine a complex RF system is desired. This report details the RF "knobs" included to meet this. | ||
| THPP004 | EMMA - the World's First Non-scaling FFAG | 3380 |
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| EMMA - the Electron Model of Many Applications - is to be built at the STFC Daresbury Laboratory in the UK and will be the first non-scaling FFAG ever constructed. EMMA will be used to demonstrate the principle of this type of accelerator and study their features in detail. The design of the machine and its hardware components are now far advanced and construction is due for completion in summer 2009. | ||
| THPP005 | Orbit Distortion and its Correction in a Non-scaling FFAG | 3383 |
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| The wide variation in betatron tune over a rapid acceleration time presents particular difficulties in orbit correction in a non-scaling FFAG. Due to the fact that the phase advance between an error source and the corrector magnets varies during acceleration, and assuming that the corrector magnets' strengths must be constant during the short acceleration period, it is clear that conventional harmonic correction is ineffective. We propose a method to determine the magnet and BPM misalignments in a non-scaling FFAG. By running the beam at fixed energy over many turns, and assuming no other error sources exist, the BPM measurements allow the misalignments to be calculated (assuming that there are as many BPMs as error sources). We show that it is also possible to calculate the BPM misalignment error if the beam is run at two fixed energies. This is due to a characteristic property of non-scaling FFAGs - the variation of the phase shift, and hence the response of the BPM measurements to magnet misalignments, with momentum. Having estimated the magnet misalignments, a local correction is made and a tracking study carried out to calculate the reduction in orbit distortion that results. | ||
| THPP006 | Injection and Extraction for the EMMA NS-FFAG | 3386 |
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| EMMA (Electron Machine with Many Applications) is a prototype non-scaling electron FFAG to be hosted at Daresbury Laboratory. NS-FFAGs related to EMMA have an unprecedented potential for medical accelerators for carbon and proton hadron therapy. It also represents a possible active element for an ADSR (Accelerator Driven Sub-critical Reactor). This paper will summarize the design of the extraction and injection transfer lines of the NS-FFAG. In order to operate EMMA, the Energy Recovery Linac Prototype (ERLP) shall be used as injector and the energy will range from 10 to 20 MeV. Because this would be the first non-scaling FFAG, it is important that as many of the bunch properties are studied as feasible, both at injection and at extraction. To do this, a complex injection line was designed consisting of a dogleg to extract the beam from ERLP, a matching section, a tomography section and some additional dipoles and quadrupoles to transport the beam to the entrance of EMMA. Further, an equivalent tomography module was placed in the extraction line together with several other diagnostic devices including the possibility of using a transverse deflecting cavity. | ||
| THPP007 | Six-sector FFAG Ring to Demonstrate Bunch Rotation for PRISM | 3389 |
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| A monochromatic muon beam is one of the most important requirements to improve a sensitivity of mu-e conversion experiments. In the PRISM project, which searches for mu-e conversion at a sensitivity of BR~10-18, makes such muon beams by using a bunch rotation technique in an FFAG ring. To demonstrate the bunch rotation, a FFAG ring has been constructed in RCNP, Osaka. The ring has six FFAG magnets and one RF cavity. Alpha particles from a radioactive isotope 241Am will circulate in the ring for the demonstration of bunch rotation. | ||
| THPP008 | Hamiltonian Approach to the Dynamics of Particles in Non-scaling FFAG Accelerators | 3392 |
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| Starting from first principle the Hamiltonian formalism for the description of the dynamics of particles in non-scaling FFAG machines has been developed. The stationary reference (closed) orbit has been found within the Hamiltonian framework. The dependence of the path length on the energy deviation has been described in terms of higher order dispersion functions. The latter have been used subsequently to specify the longitudinal part of the Hamiltonian. It has been shown that higher order phase slip coefficients should be taken into account to adequately describe the acceleration in non-scaling FFAG accelerators. | ||
| THPP009 | Injection and Extraction Orbits and Twiss Parameters for the EMMA Ring | 3395 |
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| Using the FFEMMAG code, the injection and extraction orbits for the EMMA ring at a variety of injection and extraction energies together with the Twiss parameters to be used for matching have been calculated. The orbits include two kickers together with a septum at both injection and extraction. The FFEMMAG code has been used in conjunction with several scripts so as to be able to scan the parameter space of the two kicker strengths for a section of the EMMA ring. The results confirm the choice of magnet and vacuum pipe apertures as being adequate to operate EMMA from 10 to 20 MeV. | ||
| THPP011 | Beam Acceleration Studies of Proton NS-FFAG | 3398 |
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| The NS-FFAG is a novel idea of a fixed field accelerator which has advantages in flexible design and machine operation for fixed field accelerator. However, due to the large tune variation with energy, fast acceleration is a key issue to circumvent the resonance problem in a linear NS-FFAG. At the moment, there is no numerical study of how fast it needs be. In this paper, using a lattice of a NS-FFAG for particle therapy, results of tracking study including acceleration rate, positioning tolerance are presented. | ||
| THPP012 | Beam Injection Issues of FFAG for Particle Therapy | 3401 |
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| Spot scanning irradiation is a next generation treatment scheme of particle therapy. The pulsed beam of FFAG accelerator is well fitted to the treatment. In order to form a uniform dose distribution in the target volume, intensity modulation is a requirement in spot scanning and it requires special consideration in injection in order to realize short time treatment using the pulsed beam of the FFAG. In this paper, injection related issues of NS-FFAG are discussed from the point of particle therapy, especially for spot scanning. | ||
| THPP015 | Design of a Versatile Injector for a Low-energy Experimental Platform at KACST | 3404 |
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| At the National Centre for Mathematics and Physics (NCMP), at the King Abdulaziz City for Science and Technology (KACST), Saudi Arabia, a multi-purpose low-energy experimental platform is presently being developed in collaboration with the University of Heidelberg, Germany. The aim of this project is to enable a multitude of low-energy experiments with most different kinds of ions both in single pass setups, but also with ions stored in a low-energy electrostatic storage ring. In this contribution, the injector of this complex is presented. It was designed to provide beams with energies up to 30 kV/q and will allow for switching between different ion sources from e.g. duoplasmatron to electrospray ion sources and to thus provide the users with a wide range of different beams. We present the overall layout of the injector with a focus on the optical design and the foreseen diagnostic elements. | ||
| THPP016 | Preliminary Design of a Highly-flexible Extraction Scheme for the USR | 3407 |
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| In the future Facility for Low-energy Antiproton and Ion Research (FLAIR) at GSI, the Ultra-low energy electrostatic Storage Ring (USR) will provide cooled beams of antiprotons and possibly also highly charged ions down to energies of only 20 keV/q. Beams with small momentum spread and low emittance will enable a wide range of hitherto impossible experiments. The large variety of planned experiments requires a highly flexible longitudinal time structure of the extracted bunches, ranging from ultra-short pulses in the nanosecond regime to quasi DC beams. In this contribution, a preliminary design of the extraction scheme is presented. Furthermore, possible solutions for the compensation of effects from the extraction region on the very-low energy beam are shown, including results from beam transport calculations. | ||
| THPP019 | Adjustment of a New Pre-stripping Section the Multicharge Ion Linear Accelerator (MILAC) | 3410 |
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| In the Kharkov Institute of Physics and Technology the works on commissioning of a new prestripping section (A/q = 4), intend for accelerating a high current beam of light ions from 30 keV/u to 975 keV/u come to the end. Results of final tuning of irregular interdigital accelerating structure with alternating phase focusing and stepped changing the synchronous phase along the focusing period are presented. Process of preliminary adjustment of structure by means of traditional developed earlier methods: the additional current-carrying stems and the end resonant tuning elements (ERTEs) is described. New effective inductance-capacitor tuning devices as rods located on the drift tube side, opposite to their holders («contrivance») are developed and their use in real structure is shown. «Contrivances» have proved as the effective element of tuning locally influencing value of an electric field in the nearest gaps and lowering resonant frequency without noticeable worsening of electrodynamic characteristics of resonant system. | ||
| THPP020 | Progress in the ALPI -PIAVE Low-beta Section Upgrade | 3413 |
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| The low-b section of the PIAVE-ALPI superconducting linac is being upgraded in order to increase its energy gain from approximately 10 to about 20 MeV/q. This large increase of the accelerating voltage will be obtained by increasing by 20% the number of low-beta bulk niobium quarter-wave resonators and by upgrading the old rf system, underdimensioned in comparison with the resonator performance. This will lead to a significant enhancement of the linac capabilities, including the possibility of acceleration well above the Coulomb barrier heavy ions with any mass number. Status and technical details of the upgrade program will be described. | ||
| THPP021 | Status of the Unilac-upgrade Programme for the Heavy Element Research at GSI-Ship | 3416 |
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| For more than 30 years the heavy-element research using the velocity separator SHIP is one of the major experiments at GSIs heavy ion linear accelerator UNILAC. On of the major contributions which led to the discovery of six new elements since 1981 is the perpetual effort to increase the beam intensity. Since the early 1990's the beam current available was raised significantly by a number of improvements concerning the source, the LEBT and the accelerator. The next steps are scheduled for 2009 and include an upgrade of the Radio Frequency Quadrupole-accelerator (RFQ) and a new superconducting 28 GHz-ECR ion source. The new RFQ will allow higher duty factors up to 100% and improve the longitudinal beam quality as well as the beam transmission. The new ion source will provide an increase in beam intensity and simultaneously higher charge states. The new source will be installed in addition to the existing one, therefore a second LEBT-system has to be designed and integrated into the High Charge State Injector. This paper presents the status quo of both the RFQ and the ion source upgrade and will provide technical data. | ||
| THPP022 | IH Linac with Higher-order Modes | 3419 |
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| As one of a drift tube type linac, an Interdigital H-type (IH) linac has been applied for ion acceleration in low beta range. It can realize a resonant cavity of convenient size at low frequency band and higher shunt impedance at low velocity range. These characteristics are advantageous especially for heavy ion acceleration; therefore, this structure has been applied for heavy ion cancer therapy. The RF field is resonated in TE111 mode and the electric field does not have the axial field component. The accelerating field is excited by using the electrode of Interdigital shape. In order to apply this structure to intermediate beta range, we propose a IH linac with the TE11n mode of the higher-order mode (HOM). Although the operating frequency becomes higher by using HOM, it is convenient to accelerate ion beam of intermediate energy. The design of the cavity structure and the possibility are presented. | ||
| THPP024 | Detailed Study of the RF Properties of the FETS RFQ Cold Model | 3422 |
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| A 324MHz four vane RFQ cold model has been built, as part of the development of a proton driver Front End Test Stand (FETS) at the Rutherford Appleton Laboratory (RAL) in the UK. Previous measurements to determine the electric field profile were made using the bead-pull perturbation method: these measurements have been refined and expanded. New measurements of the electric field profile, Q-value and resonant modes are presented. Measurements of the fundamental frequency and Q-value of the RFQ as a result of modifications to the profile of the end flange inserts are also given. Finally, an experiment is outlined to determine the beam transmission properties of the cold model based on beam transport simulations with the General Particle Tracer package (GPT). | ||
| THPP025 | Fabrication Status of the PEFP DTL II | 3425 |
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| The DTL II as a main part of the PEFP proton linac is under development. Following the DTL I which accelerates the proton beam up to 20 MeV, DTL II increases the proton energy from 20 MeV to 100 MeV. The DTL II consists of 7 tanks and each tank is composed of 3 sections whose length is about 2.2 m. The tank is made of seamless carbon steel and inside surface is electroplated with copper. Each drift tube contains an electroquadrupole magnet which is made of hollow conductor and iron yoke with epoxy molding. The status of development and test results of the fabricated parts are reported in this paper. | ||
| THPP026 | IH Accelerating Structures with PMQ Focusing for Low-energy Light Ions | 3428 |
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| We are developing high-efficiency room-temperature RF accelerating structures for beam velocities in the range of a few percent of the speed of light by merging two well-known ideas: inter-digital H-mode (IH) cavities and the transverse beam focusing with permanent-magnet quadrupoles (PMQ). Combining electromagnetic 3-D modeling with beam dynamics simulations and thermal-stress analysis, we have proved that such structures provide a very efficient and practical accelerator for light-ion beams of considerable currents. The IH accelerating structures with PMQ focusing following a short RFQ can be used in the front end of ion linacs or in stand-alone applications such as a compact deuteron-beam accelerator up to the energy of a few MeV. | ||
| THPP027 | Heating and Stress in the LANSCE Side-coupled Linac RF Cavities | 3431 |
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| RF heating and related temperature distribution and stress are important problems in room-temperature accelerating cavities operating at high duty factors. To evaluate feasibility of higher duty operations of the Los Alamos Neutron Science Center (LANSCE) side-coupled linac (SCL), we have performed a combined 3-D electromagnetic (EM) and thermal-stress analysis of the SCL RF cavities. In the process, we have developed a procedure and interface for data exchange between the electromagnetic (MicroWave Studio) and engineering (COSMOS) codes for the combined EM-engineering analysis. This interface can be useful for other applications involving room-temperature accelerating cavities. | ||
| THPP028 | Beam Tests of the PEFP 20 MeV Accelerator | 3434 |
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| PEFP (Proton Engineering Frontier Project) 20 MeV proton accelerator has been installed and tested at KAERI (Korea Atomic Energy Research Institute) site. After the radiation license was issued, some parts were modified to increase a beam current above 1mA. Both an ion source and a LEBT (Low Energy Beam Transport) were modified for better matching of the beam into the 3 MeV RFQ. The field profile of the RFQ was measured to check the dipole field effect. In addition, control mechanisms to improve the RF properties of 20 MeV DTL were newly adopted. In this paper, the modifications of the 20MeV accelerator are summarized and the test results are presented. | ||
| THPP029 | Status of the RAL Front End Test Stand | 3437 |
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| High power proton accelerators (HPPAs) with beam powers in the several megawatt range have many applications including drivers for spallation neutron sources, neutrino factories, waste transmuters and tritium production facilities. The UK's commitment to the development of the next generation of HPPAs is demonstrated by a test stand being constructed in collaboration between RAL, Imperial College London, the University of Warwick and the Universidad del Pais Vasco, Bilbao. The aim of the RAL Front End Test Stand is to demonstrate that chopped low energy beams of high quality can be produced and is intended to allow generic experiments exploring a variety of operational conditions. This paper describes the current status of the RAL Front End Test Stand. | ||
| THPP031 | Upgrade of the ISAC DTL Tuning Procedure at TRIUMF | 3440 |
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| The TRIUMF ISAC facility has two variable energy heavy ion linacs as post accelerators for radioactive ion beams. The ISAC I linac is a warm IH-DTL with five accelerating tanks and three bunchers, the ISAC II one uses twenty independently phased superconducting cavities. The first linac operates between 150 keV/u and 1.8 MeV/u; the second boosts the 1.5 MeV/u injected beam by 20 MV. The DTL is tuned based on the energy beam profile given by an analysing magnet. The SC linac is tuned on energy and time profiles with a diagnostic based on a gold foil scattering ions to a silicon detector (SID). The SID requires lower beam intensity. Furthermore the tuning time is reduced and streamlined by means of a MATLAB graphical user interface (GUI). This GUI uses a simple cosine model to characterize the energy gain versus RF phase of each cavity. Based on this we have pursued a new tuning procedure for the DTL using a gold foil/SID diagnostic. The more complex RF structures of the DTL require measurements and beam dynamics simulations (with LANA code) to produce a model for a dedicated GUI. In the paper we describe the two existing tuning methods and present new DTL procedure and interface. | ||
| THPP034 | Design Study of Alternate Injector at Pelletron Accelerator Facility | 3443 |
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| An alternate injector system is contrived under the AIDNP project in the Xth plan to utilize the 150MHz supercond. LINAC to its full capability. This injection system consists of ECR ion source, RFQ Linac and supercond. QWR cavities. This configuration can deliver high current and wider mass range(1/7≤ q/m≤1/2) beam into the S-LINAC with the required velocity acceptance which otherwise is not possible from pelletron. The design study from ion source to exit of RFQ is presented in this paper. Prior to injection to s-linac,the beam needs to be accelerated to an equivalent of 12-14MV/q. Beam from a high frequency(18GHz) ECRsource producing Au30+,U34+ and pre accelerated to 10keV/u will be injected into heavy ion RFQ. The RFQ operating at f/2 i.e.75MHz of the linac frequency, will accept beams with β=0.46% and accelerate upto β=3.5%.These beams would then go through two sets of superconductiong cavities with β=5.0% and β=7.0% respectively. This acceleration is expected to bring all ion beams from carbon to uranium, in the velocity range β=8%-10% which is suitable for linac. After further acceleration in Linac~12 MeV/u light ions and 7 MeV/u uranium beams would be available. | ||
| THPP036 | The Superconducting Solution for the EURISOL DS Postaccelerator Injector | 3446 |
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In the framework of EURISOL design study*, the superconducting solution for the Post-Accelerator injector foresees the use of two RFQs, one Super Conducting and one Normal Conducting, both operating CW at 88 MHz. After the multiple ionization in the ECR breeder on low voltage platform, the rare ions beam (3 ≤ A/q ≤ 7) is bunched at the main frequency by the NC RFQ without both losses and transverse emittance increase and accelerated afterwards through the SC RFQ up to 560 keV/u. A 8.8 MHz pulsed beam can be delivered to experiments placing a 3 harmonic buncher before the NC RFQ with overall beam losses lower than 25%. The beam dynamics results of the study of this solution as well as the main RF design and construction analysis of the main components are presented.
*http://www.eurisol.org |
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| THPP037 | A Decelerator for Heavy Highly Charge Ions at HITRAP | 3449 |
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| The heavy highly charged ion trap (HITRAP) project at GSI is in the commissioning phase. Highly charged ions up to U92+ provided by the GSI accelerator facility will be decelerated and subsequently injected into a large Penning trap for further cooling almost to rest. A combination of an IH- and an RFQ-structure decelerates the ions from 4 MeV/u down to 6 keV/u. In front of the decelerator a double drift-buncher-system provides for phase focusing and a final de-buncher integrated in the RFQ-tank reduces the energy spread in order to improve the efficiency for beam capture in the cooler trap. This contribution concentrates on the beam dynamics simulations and corresponding measurements in the first commissioning beam times. | ||
| THPP038 | Phase 1 Commissioning Status of the 40 MeV Proton/Deuteron Accelerator SARAF | 3452 |
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| Since January 2007 all accelerator equipment of the Phase 1 for the 40MeV Proton/Deuteron Accelerator is at the SARAF site and installed for the commissioning. The target of Phase 1 is to get the ECR ion source and RFQ into operation and to perform all relevant test with the cryo module housing 6 super conducting half wave resonators, to show that the design values of the system can be reached. Based on those results the Phase 2 shall start, to reach the final energy of 40MeV with up to 2mA of Protons and Deuterons. The ECR source is in routine operation since June 2006, the RFQ already have been operated with Protons and currently is under characterisation. After the characterisation has been finalised it is anticipated to move the cryo module in the beam line and to perform further beam characterisation. The entire beam characterisation is closely followed by beam dynamics simulations. Recent results of the commissioning will be presented and comparisons made between measurements and beam dynamics calculations. | ||
| THPP040 | Choice of Accelerating System for Undulator Linear Accelerator | 3455 |
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The undulator linear accelerators (UNDULAC) were suggested as a new type of high intensity low energy ion linac. Such accelerators can be realized in periodical IH structure. The RF field in UNDULAC has no spatial harmonics in synchronism with the beam*. An accelerating force is to be driven by a combination of two non-synchronous space harmonics. The ratio of first to zero RF field harmonics amplitude must be equal to 0.25-0.4. The effective beam bunching and focusing could be provided in this case. The construction of UNDULAC accelerating channel is discussed to realize such ratio. The first results of IH resonator type choice are also presented.
*E. S. Masunov, Technical Physics, V. 46, 11, 2001, pp. 1433-1436. |
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| THPP041 | Beam Dynamics Simulation of the 1.5 MeV/u Proton/Deuteron Beams Measured at the SARAF RFQ Exit | 3458 |
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| The Soreq Applied Research Accelerator Facility (SARAF) accelerator's front-end is composed of a 20 keV/u protons and deuterons ECR ion source, a 5 mA low energy beam transport and a 1.5 MeV/u, 4 mA, 176 MHz, 4-rod RFQ. In this work, beam dynamics simulations of the SARAF accelerator front-end is compared to the first beam measurements taken during commissioning. Beam transmission, ion energy and bunch width as a function of the RFQ power have been measured in the medium energy beam transport diagnostics and using a dedicated diagnostic plate. The simulations and measurements show similar trends. This agreement allows calibrating the RFQ power to its electrodes voltage, in the low electric field range, where the common x-ray measurement method is not feasible. The benchmark between simulation and measurement shows that the RFQ model in our simulation can well predict the measured values. The simulation is covering the beam tail as well and is used to find the optimal operating voltage by minimizing the low energy tail and hence the beam loss downstream the accelerator. | ||
| THPP044 | Experience with the SNS SC Linac | 3461 |
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The SNS SC linac (SCL) is designed to deliver 1 GeV, up to 1.56 MW pulsed H- beams for neutron production. Beam commissioning of the SNS accelerator systems completed in June 2006 with the maximum linac output beam energy approximately 952 MeV. In 2007, we successfully tuned the SCL for 1 GeV beams during a test run, and the SNS linac achieved its design energy for the first time. During the linac tune-up, phase scan signature matching, drifting beam measurement as well as linac RF cavity phase scaling was applied. In this paper, we will introduce the experiences with the SCL, and we will also briefly discuss beam parameter measurements.
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| THPP046 | Applicability of Stochastic Cooling in Small Electrostatic Storage Rings | 3464 |
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Several small electrostatic storage rings have been built or are being built for experiments in atomic and molecular physics. One example is the DESIREE double electrostatic storage ring* under construction at the Manne Siegbahn Laboratory. At the KEK electrostatic storage ring, electron cooling of 20 keV protons has been demostrated**. For heavy molecules, however, including bio-molecules, electron-cooling times are unrealistically long because of the low ion velocity and the correspondingly low electron energy which results in very small electron currents. For this reason, electron cooling is not foreseen for DESIREE. The rates of stochastic cooling, on the other hand, are at first glance unrelated to beam energy. Furthermore, the low particle numbers expected for many heavy molecules seem to make stochastic cooling attractive, theoretical rates being inversely proportional to particle numbers. In this paper, the rates of stochastic cooling for slow heavy particles are investigated with respect to, mainly, the bandwidths and signal strengths that can be expected at the low particle velocieties that are of interest at, e.g., DESIREE, and some numerical examples are presented.
* P. Löfgren et al., these proceedings |
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| THPP047 | Prototype of the High Voltage Section for the 2 MeV Electron Cooler at COSY | 3467 |
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| The design, construction and installation of a 2 MeV electron cooling system for COSY-Juelich is proposed to further boost the luminosity even with strong heating effects of high-density internal targets. In addition the 2 MeV electron cooler for COSY is intended to test some new features of the high energy electron cooler for HESR at FAIR/GSI. The design of the 2 MeV electron cooler will be accomplished in cooperation with the Budker Institute of Nuclear Physics in Novosibirsk, Russia. The design and first experiments of a new developed prototype of the high voltage section, consisting of a gas turbine, magnetic coils and high voltage generator with electronics is reported. | ||
| THPP048 | Experimental Demonstration of Longitudinal Ion Beam Accumulation with Electron Cooling | 3470 |
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Recently, two longitudinal beam compression schemes have been successfully tested in the Experimental Storage Ring (ESR) at GSI with a beam of bare Ar ions at 65 MeV/u injected from the ion synchrotron SIS18. The first employs Barrier Bucket pulses, the second makes use of multiple injections around the unstable fixed point of a sinusoidal RF bucket at h=1. In both cases continuous electron cooling maintains the stack and merges it with the freshly injected bunch *. Using the beam diagnostic devices in the ring both stacking processes were demonstrated under the same conditions. The dependence of the accumulation performance on the available rf potential, the electron cooling strength as well as on the synchronization conditions between injection kicker pulse and rf wave was investigated. These experimental results provide the proof of principle for the planned fast stacking of Rare Isotope Beams aiming at high luminosities in the New Experimental Storage Ring ** of the FAIR project ***.
* C. Dimopoulou et al., JACoW Proceedings of COOL07, Bad Kreuznach,2007. |
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| THPP049 | Status of Electron Cooler Design for HESR | 3473 |
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| The HESR-ring of the future FAIR-facility at GSI will include both electron cooling and stochastic cooling in order to achieve the demanding beam parameters required by the PANDA experiment. The high-energy electron cooler will cool antiprotons in the energy range 0.8 GeV to 8 GeV. The design is based on an electrostatic accelerator and shall not exclude a further upgrade to the full energy of HESR, 14.1 GeV. The paper will discuss prototype tests of critical components and recent development in the design including the high-voltage tank, electron gun and collector, magnet system, electron beam diagnostics and the magnetic field measuring system. | ||
| THPP050 | Recent Status of Laser Cooling for Mg Realized at S-LSR | 3476 |
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At an ion storage and cooler ring, S-LSR, a laser cooling has been applied to the 40 keV 24Mg+ ion beam guiding a laser with the wave length of 280nm parallel to the ion beam together with the deceleration by an induction voltage. Up to now, the longitudinal temperature has been cooled down to 3.6 Kelvin for the ion number of 3x104 although the transverse one still remains around 500 Kelvin. The longitudinal temperature is limited by the heat transfer from the transverse degree of freedom through intra-beam scattering, which becomes stronger according to increase of ion number. It is found that the equilibrium longitudinal temperature is linearly coupled with the transverse one* for our experimental condition up to now. In the present paper, recent experimental data will be presented together with the procedure of beam diagnosis with the use of optical methods using a spontaneous emission of the Mg ions. Possible approach to realize the resonant coupling through synchro-betatron coupling** is also to be presented.
* M. Tanabe et al., To be published in Applied Physics Express (APEX). |
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| THPP051 | Stochastic Cooling in the Framework of the FAIR Project at GSI | 3479 |
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| Stochastic cooling at FAIR will be one of the instruments to get cooled beams of rare isotopes and antiprotons for high resolution experiments. Stochastic cooling systems will be installed in the CR and RESR storage rings. The Collector Ring CR is a dedicated storage ring for the first step cooling of antiproton beams (3 GeV or β=0.97) produced at the antiproton production target, and of radioactive beams (740 MeV/u or β=0.83) prepared in the Super Fragment Separator. The pick-up and kicker systems have designs which allow very efficient cooling for both particle velocities. There will be different ring optical settings for optimum cooling of antiprotons or rare isotopes. Whereas the next cooling step for rare isotopes will be electron cooling, antiprotons will be accumulated in the RESR using a similar accumulation scheme which was formerly applied at the AA at CERN. The paper presents the CR and RESR system layouts and new hardware developments. | ||
| THPP052 | Electron Cooling Force Calculations for HESR | 3482 |
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| The High energy storage ring HESR at FAIR is being realized by a consortium consisting of Forschungszentrum Jülich, GSI Darmstadt and Uppsala University. An important feature of this new facility is the combination of phase-space cooled beams and dense internal targets. Charmonium spectroscopy, which is one of the main items in the experimental program, requires antiproton momentum up to 8.9 GeV/c with a resolution of dp/p=0.00001. This can only be achived with electron cooling. The electron cooler proposed for HESR allows beam cooling between 1.5 GeV/c and 8.9 GeV/c. Along the 24 m interaction section beween electrons and antiprotons, the electrons are guided by a solenoid field of 0.2 T with a field straightness of 0.00001 radians rms. To predict the final momentum resolution of the antiproton beam in HESR, electron cooling force calculations, simulations of electron cooling and comparison to experimental data are needed. This paper focuses on the force calculations. The method is based on the theory by Derbenev and Skrinsky, (i.e. the Vlasov techique) and the electron cooling force is numerically calulated using adaptive Monte Carlo integration methods. | ||
| THPP053 | One-dimensional Ordering of Protons by the Electron Cooling | 3485 |
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| One of the main subjects of the compact cooler ring, S-LSR at Kyoto University is the physics of the ultra cold ion beam, such as the ordered beam and the crystalline beam, using the electron and laser cooling. The one-dimensional ordering of protons has been studied at S-LSR, while the ordering the highly charged heavy ions has been found at ESR and CRYRING. Abrupt jumps in the momentum spread and the Schottky noise power have been observed for protons at a particle number of around 2000. The beam temperature was 0.17 meV and 1 meV in the longitudinal and transverse directions at the transition, respectively. The normalized transition temperature of protons is close to those of heavy ions at ESR. The lowest longitudinal beam temperature below the transition was 0.3 K. It is close to the longitudinal electron temperature. The dependence of the ordering conditions on the betatron tune and the transverse beam temperature have been also studied. These results will be presented in the presentation. | ||
| THPP054 | Laser Cooling of Bunched Ion Beam at S-LSR | 3488 |
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S-LSR is an ion storage ring equipped with an electron cooler and a laser cooling system. The laser cooling experiments of coasting beams were carried out during last year*. Now we started bunched beam laser cooling. 40keV Mg+ beams are bunched by an untuned RF cavity for harmonic number 5-50, and is cooled by a single 280nm laser. Bunch length are measured by electrostatic pickups. When RF harmonic number is five, bunch lengths is shorten from 1m to under 0.14m by laser cooling. Since the bunch length after cooling is shorter than present monitor resolution, fluorescence measurement is in preparation. We have installed another small RF cavity for harmonic number 100. Synchrotron-betatron coupling will be induced by dispersion at the place of this cavity**. This effect is expected to realize three dimensional laser cooling. In this paper we present the result of bunched beam cooling and the trial to three dimensional laser cooling.
*M. Tanabe et al. Appl. Phys. Express, in press. |
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| THPP055 | Stochastic Cooling Developments for the HESR at FAIR | 3491 |
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| The High-Energy Storage Ring (HESR) of the future International Facility for Antiproton and Ion Research (FAIR) at the GSI in Darmstadt will be built as an anti-proton cooler ring in the momentum range from 1.5 to 15 GeV/c. An important and challenging feature of the new facility is the combination of phase space cooled beams with internal targets. In addition to electron cooling transverse and longitudinal stochastic cooling are envisaged to accomplish these goals. A detailed numerical analysis of the Fokker-Planck equation for longitudinal filter cooling including an internal target and intrabeam scattering has been carried out to demonstrate the stochastic cooling capability in the newly designed normal conducting ring lattice of the HESR. Theoretical predictions have been compared to experimental cooling results with internal targets at the COSY facility. Recent developments for the HESR stochastic cooling equipment will be discussed. The design of new high sensitive printed loop couplers and ring slot couplers for the (2-4) GHz range as well as prototype measurements with protons in the COSY accelerator will be presented. | ||
| THPP056 | Simulations of Incoherent Vertical Ion Losses and Cooling Stacking Injection | 3494 |
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| The cooling stacking injection at a synchrotron is applied to obtain a high intensity of the stored coasting ion beam. The efficiency of cooling-stacking injection is defined mainly by two parameters: the cooling-accumulation efficiency and the ion life time. The life time of new injected ions usually is essentially smaller than the stack life time for high intensive ion beams. The incoherent loses of new injected ions are related to a multi scattering on residual gas atoms and a vertical heating caused by ion stack noise. The short life time of new injected ions restricts the efficiency of the cooling stacking injection The life time of new injected C6+ ions is shorter by 2 times than stack life time at HIMAC cooling stacking injection. The life time of new injected protons in S-LSR is smaller by 2-3 orders of magnitudes than the stack life time. The analytical estimations and BETACOL simulations of vertical incoherent ion losses and cooling stacking injection are presented. | ||
| THPP057 | Electron Cooling Experiments at LEIR | 3497 |
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| The LEIR electron cooler is the first of a new generation of coolers utilising high-perveance variable-density electron beams for the cooling and accumulation of heavy ion beams. It was commissioned at the end of 2005 and has since been routinely used to provide high brightness Pb ion beams required for future LHC ion runs. High perveance, or intensity, is required to rapidly reduce the phase-space dimensions of a newly injected “hot” beam whilst the variable density helps to efficiently cool particles with large betatron oscillations and at the same time improve the lifetime of the cooled stack. In this report we present the results of recent measurements made to check and to better understand the influence of the electron beam size, intensity and density profile on the cooling performance. | ||
| THPP058 | Progress with Electron Beam System for the Tevatron Electron Lenses | 3500 |
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| We have developed , built and tested two novel electron guns for the Tevatron and RHIC electron lenses: the first, a gridded gun which generates electron beam profile with smoothed edges and broad flat-top; the second, Gaussian beam profile gun which can be used for generation of the profile with depressed emission in the center. We have also developed a new type of HV modulator for use in TELs. In this articel, we desicribe the guns and the modulator, and present results of the bench tests. | ||
| THPP060 | Simultaneous Extraction of Two Stable Beams for ISAC | 3503 |
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| The TRIUMF cyclotron was originally conceived for several proton beams extracted simultaneously at different energies. Recent operation includes a 500 MeV beam up to150 μA for meson users, a 500 MeV beam up to 80 μA for rare isotope production, and a 100 MeV beam up to 70μA for medical isotopes. The extraction of an additional high intensity proton beam, at an energy between 450 and 500 MeV for ISAC has now been given priority. With the rare ions produced from the existing and future primary beam lines, we will be able to operate two of the existing experimental areas simultaneously. Upgrading the cyclotron for higher intensity is in progress. A necessary goal for ISAC is the extraction of both primary proton beams with stability better than 1% to allow the highest possible temperatures to be reliably maintained at the ion production targets. A successful solution implemented for the existing primary ISAC beam has been simulated to be adaptable for both primary beams, given the particular angular separation between the two strippers in the cyclotron. Progress on intensity and stability studies and the layout of the extraction system will be presented. | ||
| THPP063 | Possible Particle Distributions at the Entrance of the Cyclotron Spiral Inflector | 3506 |
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| The transverse particle distribution of the ion beam produced in the Electron Cyclotron Resonance Ion Source (ECRIS) is considered. It is shown that the beam emittance at the entrance of the cyclotron spiral inflector is strongly dependent on directions of both the ECRIS and cyclotron magnetic fields. The changing of the beam rms emittance and bunch lengthening in the spiral inflector for every considered distribution are obtained in the computer simulation. | ||
| THPP065 | 3D Simulation of the Axial Injection Beam Line of DC350 Cyclotron | 3509 |
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| DC-350 is the novel cyclotron designed in Flerov Laboratory of Nuclear Reaction of Joint Institute for Nuclear Research. It is intended for the nuclear and applied physics experiments. The axial injection channel of the DC-350 cyclotron gives possibility for transportation of the high intensity ion beam from Li to Bi obtained in the superconducting ECR-ion source (SECR). The beam focusing in the beam line after the analyzing bending magnet is provided by solenoidal lenses. The linear and sinusoidal bunchers installed in the vertical part of the channel are used for increasing of the accelerating efficiency. The 3D simulation results of the focusing and bunching systems of the axial injection beam line are presented. | ||
| THPP067 | An Intense Neutron Source with Emittance Recovery Internal Target (ERIT) Using Ionization Cooling | 3512 |
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| An intense neutron source with emittance recovery internal target (ERIT) using ionization cooler ring has been developed at Kyoto University Research Reactor Institute (KURRI) for boron neutron capture therapy (BNCT). The neutron source consists of a 11MeV H- linac and a FFAG storage ring. A thin (10micron) Be target is placed in the ring. In order to reduce an emittance growth caused by multiple scattering at the target, an ionization cooling with a low frequency and high voltage RF cavity is utilized. The beam is expected to be survived for more than 500 turns in the ring, which can increase beam efficiency largely to reduce an injected beam current. | ||
| THPP068 | Acceleration in spiral FFAG using field map data | 3515 |
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| This paper presents beam dynamics studies regarding the variable energy operation of a spiral scaling FFAG (Fixed Field Alternating Gradient) accelerator designed for producing 70 to 180 MeV protons and acceleration simulations for different operation modes, corresponding to different extraction energies. | ||
| THPP069 | Status of the Superconducting Ring Cyclotron at RIKEN RI Beam Factory | 3518 |
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| A superconducting ring cyclotron (SRC) was successfully commissioned to work as the final energy booster of the RI beam factory (RIBF) in RIKEN. SRC is the world's first ring cyclotron that uses superconducting magnets, and has the strongest beam bending force among the cyclotrons. It can boost the ion beam energy up to 440 MeV/nucleon for light ions and 350 MeV/nucleon for very heavy ions such as uranium nuclei to produce intense radioactive beams. The ring cyclotron consists of 6 major superconducting sector magnets with a maximum field of 3.8T. The total stored energy is 240MJ, and its overall sizes are 19 m diameter, 8 m height and 8,100 tons. The magnet system assembly was completed in August 2005, and successfully reached the maximum field in November 2005. After magnetic field measurements for two months, the other hardware than the superconducting magnets was installed. The first beam was extracted from SRC on 12/28/2006. From May 2007 we started to supply uranium beams to nuclear scientist to produce RI beams. This talk will describe the milestones that were achieved during the commissioning as well as some of the issues that still need to be resolved. | ||
| THPP070 | Status of Center for Accelerator and Beam Applied Science of Kyushu University | 3521 |
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| A new accelerator facility of Center for Accelerator and Beam Applied Science is under construction on Ito Campus to promote research and education activities at Kyushu University. The facility consists mainly of a 10 MeV proton cyclotron as an injector and a 150 MeV Fixed Field Alternating Gradient (FFAG) accelerator, which was developed at KEK as a prototype of proton FFAG for various applications. In this paper, the status of the development of devices and the facility is described. | ||
| THPP071 | Construction of Six-sector FFAG Ring for Muon Phase Rotation | 3524 |
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| PRISM is a next-generation of muon source which provides high purity, high intense and high brightness beam. In PRISM, a PRISM-FFAG is one of key section which make a muon beam narrow energy width by using phase rotation technique. To demonstrate the phase rotation, a six-cell FFAG ring has been constructed; the ring consists of full size of scaling-FFAG magnets and a high gradient rf cavity. The experiment is achieved by injecting alpha particles from a radioisotope source as a beam. Construction of the ring has been started from September, 2007; beam duct has been designed and installed, the six FFAG magnets has been aligned, etc. In this paper, we will present the design of the ring and the construction (alignment, etc) from engineering point of view. | ||
| THPP072 | Extinction Monitor by Using a Dissociation of Hydrogen Molecule to Atoms with High Energy Proton Beam | 3527 |
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| In a recent high current accelerator technology there are so many reasons for resulting in unwanted or hallow beam to be coped with, such as resonance crossing, space charge induced emittance growth and so on. For an extinction for bunched beam of less than 10-7 order we need a particular scheme to diminish unwanted and hallow beam generated at not only spatial plane but also at longitudinal plane. In particular, the beam extinction between beam bunch is crucial for delayed coincidence measurements of intensity frontier and high sensitivity experiment such as muon to electron conversion and muon to electron gamma. The new detection method for the extinction is proposed by using a collision dissociation between a high energy proton with more than GeV energy and molecular ions. One path collision of high energy beam for molecular ion beam to be separated into atoms as well as its collision between stored molecular ions and high energy particles could be exploited for the monitor. | ||
| THPP073 | Performance of the SNS Front End and Warm Linac | 3530 |
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| The Spallation Neutron Source accelerator systems will deliver a 1.0 GeV, 1.4 MW proton beam to a liquid mercury target for neutron scattering research. The accelerator complex consists of an H- injector, capable of producing one-ms-long pulses at 60 Hz repetition rate with 38 mA peak current, a 1 GeV linear accelerator, an accumulator ring and associated transport lines. The 2.5 MeV beam from the Front End is accelerated to 86 MeV in the Drift Tube Linac, then to 185 MeV in a Coupled-Cavity Linac and finally to 1 GeV in the Superconducting Linac. With the completion of beam commissioning, the accelerator complex began operation in June 2006 and beam power is being gradually ramped up toward the design goal. Operational experience with the injector and linac will be presented including chopper performance, longitudinal beam dynamics study, and the results of a beam loss study. | ||
| THPP074 | Optimal Design of a High Current MEBT with Chopper | 3533 |
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| Many existing and proposed projects require a certain temporal structure imposed on the beam pulse, e.g., creating gaps for low-loss extraction from a circular accelerator. Usually it is achieved using chopper systems. In order to reduce average beam power on the target and simplify kicker requirements chopper system is located in a lower energy part of the accelerator, typically in the medium energy transport line (MEBT) between the RFQ and the linac. Many of the MEBT layouts, proposed and in use, look very much alike and try to achieve a compromise between two opposing requirements of providing strong transverse focusing and sufficiently long empty drifts for the kickers. As a result, both requirements are not fully satisfied leading to space charge induced emittance increase and very challenging technical specifications for the kicker and its power supply. These difficulties quickly increase with the beam current. We propose a different MEBT layout, which does not compromise quality of beam transport and allows space for a kicker with any reasonable parameters. A generic design of a 5.5m long MEBT transporting 100mA with emittance increase of less than 5% is shown as an example. | ||
| THPP075 | Beam Dynamics of the IFMIF-EVEDA RFQ | 3536 |
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| The IFMIF project is aimed at the realization of an intense neutron beam facility for testing the irradiation of the materials to be used for fusion reactors. EVEDA (Engineering Validation Engineering Design Activities) is a first step towards the implementation of this challenging project and consists of the construction of prototypes of the main units. In particular INFN-LNL is in charge of the construction of a 5 MeV, 125 mA, deuteron RFQ at 175 MHz. In this article the main aspects of the beam dynamics design of this RFQ are described, namely the optimization of the length and the transmission issues, the main outcomes and comparison of the PARMTEQM and TOUTATIS codes used for the simulations and the basic aspects of the errors studies. | ||
| THPP077 | The IFMIF-EVEDA Accelerator Activities | 3539 |
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| The International Fusion Materials Irradiation Facility (IFMIF) aims at producing an intense flux of 14 MeV neutrons, in order to characterize materials envisaged for future fusion reactors. This facility is based on two high power CW accelerator drivers, each delivering a 125 mA deuteron beam at 40 MeV to the common lithium target. In the framework of the EU-JA Bilateral Agreement for the Broader Approach for Fusion, the Engineering Validation and Engineering Design Activities (EVEDA) phase of IFMIF has been launched in the middle of 2007. The objectives of EVEDA are to produce the detailed design of the entire IFMIF facility, as well as to build and test a number of prototypes, including a high-intensity CW deuteron accelerator (125 mA @ 9 MeV). The major components and subsystems will be designed and developed in Europe, and will be then assembled and operated at Rokkasho in Japan. The individual components are developed in Spain, Italy and France and an european accelerator team has been settled for the coordination of the accelerator activities. The design and the layout of the accelerator are presented as well as the development schedule. | ||
| THPP078 | IFMIF-EVEDA RFQ Design | 3542 |
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| The RFQ of IFMIF-EVEDA project is characterized by very challenging specifications, with 125 mA of deuteron accelerated up to 5 MeV. After the long period of conceptual and comprehensive design of IFMIF accelerator, the decision of the construction of its low energy part has implied a new analysis of the RFQ design. In particular the beam dynamics design has been optimized, with a consistent reduction of the structure length and power consumption, and improvement of the performances in terms of beam losses. The resonator, of four vanes kind, has been designed taking advantage of the theoretical background and experimental experience gained in Europe with IPHI and TRASCO projects. The mechanical design has been analysed considering different approaches, involving vacuum brazing, laser or e'beam welding. | ||
| THPP079 | Design of the High Current Linac of SPES Project | 3545 |
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| The proposed driver, composed by a four vanes RFQ and an Alvarez DTL, generates a high intensity beam, for an average current of 1.5 mA and an energy of 43 MeV, upgradable to 95 MeV. The high rep rate (50 Hz) is necessary for the correct mechanical behavior of the target. The accelerator is composed by the source TRIPS, built at LNS and now in operation at LNL, by the RFQ of TRASCO research program (5 MeV 30 mA), very advanced in the construction, and by a normal conducting Drift Tube Linac (DTL). This last accelerating structure is the same proposed for LINAC4 at CERN. A prototype of this structure, of interest for both projects, is in construction in Italy with the joint effort of CERN and LNL. The RFQ and the two tanks of the DTL are fed by 3 klystrons; the first one, with a power of 1.3 MW, is already at LNL, while the other two with a power of 2.5 MW each are the same adopted for LINAC4. The power supply of the RF system (50 Hz 0.6 ms) has been evaluated in details on the bases of the system in operation for the Japanese project JPARC. This paper illustrates the physical design and beam dynamics studies of this linac. | ||
| THPP080 | A Superconducting CH-Linac for IFMIF | 3548 |
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| The IFMIF accelerator which has to provide a 40 MeV 250 mA Deuteron beam requires a duty cycle of 100%. The IAP Frankfurt has proposed 175 MHz H-type drift tube linac consisting of an IH-cavity and a chain of superconducting CH-cavities. A superconducting CH-prototype cavity has been tested very successfully and reached effective gradients of 7 MV/m. Two rf power couplers are necessary to feed one CH-cavity. The maximum rf power per cavity is approximately 500 kW. As amplifiers the originally foreseen 1 MW tubes or 300 kW tubes can be used. The focusing scheme in the CH-linac is based on superconducting solenoids. Beam dynamics simulations have been performed with an error analysis using the LORASR code based on the KONUS dynamics. An updated and improved linac design will be presented. A contribution of IAP for the EVEDA phase could consists of the construction and the test of the room temperature IH-cavity and the first complete CH cryo-module. A study together with industry has been already performed regarding the production process and the system integration of auxiliary equipment like couplers and tuner. | ||
| THPP082 | Residual Activity Induced by High-energy Heavy Ions in Stainless Steel and Copper | 3551 |
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| The activation of accelerator structures due to beam loss is already intensity limiting problem for existing (SNS or RHIC) and planned (LHC or FAIR) hadron facilities. While beam-losses of 1 W/m are recognized as a tolerable beam-loss level for proton machines, the beam-loss tolerances for high-power heavy-ion accelerators have not yet been quantified. In this work the residual activity was calculated by Monte-Carlo particle transport codes and compared with experimental data. Simulations were performed for projectiles from proton to uranium. Experiments were performed with uranium ions at 120, 500 and 950 MeV/u irradiating copper and stainless steel targets. It was found that the isotope inventory contributing over 90% to the total activity does not depend on the projectile species, it depends only on the target material and projectile energy. This allowed establishing a scaling law for induced activity as a function of ion mass. The activity per nucleon induced by ion scales down with increasing ion mass. For example, 1 GeV/u uranium ion induces 5-times less activity per nucleon compared to 1 GeV proton. The beam-loss criteria for different projectile species are presented. | ||
| THPP083 | Megawatt Upgrades for the ISIS Facility | 3554 |
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| ISIS is the spallation neutron source at the Rutherford Appleton Laboratory in the UK. Presently, it runs at beam powers of 0.2 MW, with upgrades in place to supply increased powers for the new Second Target Station due to start operation in autumn 2008. This paper outlines schemes for major upgrades to the facility in the megawatt regime, with options for 1, 2 and 5 MW. The ideas centre around new 3.2 GeV RCS designs that can be employed to increase the energy of the existing ISIS beam to provide powers of ~1 MW or, possibly as a second upgrade stage, accumulate and accelerate beam from a new 0.8 GeV linac for 2-5 MW beams. Summaries of ring designs are presented, along with studies and simulations to assess the key loss mechanisms that will impose intensity limitations. Important factors include injection, RF systems, instabilities, longitudinal and transverse space charge. | ||
| THPP084 | Discussion on RCS versus AR on the Basis of J-PARC Beam Commissioning for Pulsed Spallation Neutron Source | 3557 |
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| Over a decade it is one of the most controversial issues regarding the accelerator scheme choice whether RCS or AR should be chosen for the pulsed spallation neutron source. In order to simplify the discussion, we compare 3-GeV RCS with 1-GeV AR. The former is J-PARC scheme while the latter is SNS scheme. To summarize the discussion, RCS technology is much more difficult than AR technology, although RCS has many advantages over AR arising from its low beam current for the same beam power. Now, the J-PARC 3-GeV RCS was actually commissioned. On the basis of its experience, the discussion will be resumed. | ||
| THPP085 | Status of the SNS Ring Power Ramp Up | 3560 |
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| Beam was first circulated in the SNS ring in January 2006. Since that time we have been working to raise the beam power to the design value of 1.4 MW. In general the power ramp up has been proceeding very well, but several issues have been uncovered. Examples include poor transmission of the waste beams in the injection dump beam line, cross-plane coupling in the ring to target beam transport line, and higher-than-expected peak densities in the ring to target transport. In this paper we will discuss these issues and present an overall status of the ring and the transport beam lines. | ||
| THPP086 | Diamond Stripper Foil Experience at SNS and PSR | 3563 |
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||
| The SNS is currently operating at about 15% of the 1.4 MW design power, and the diamond stripper foils developed at ORNL continue to perform well. Several corrugated, nanocrystalline diamond stripping foils have been tested at SNS. Beyond about 300 C of injected charge, significant distortion and darkening of the foils is observed. These foils are currently limited in freestanding area to about 17x25 mm due to stress-induced tears in larger foils; this limit positions the residual silicon wafer mounting handle close enough to the circulating beam that additional losses have been observed. The PSR experience with these diamond foils has been promising, with the interesting observation that both the foil current due to secondary emission of electrons and the thermionic foil current are reduced for diamond foils relative to LANL/KEK foils. For comparable thickness foils, losses due to the Ho yield also appear to be higher for diamond. A recent development in our foil preparation has been a change to nano-seeded nucleation from the earlier microcrystal slurry ultrasonic abrasion technique. This has led to a more reproducible and uniform foil morphology with smaller crystallites. | ||
| THPP087 | 4 GeV H- Charge Exchange Injection into the PS2 | 3566 |
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| The proposed PS2 will accelerate protons from 4 to 50 GeV. The required beam intensity and brightness can only be achieved with a multi-turn H- charge exchange injection system, where the small emittance injected beam is used to paint the transverse phase space of the PS2 machine. This paper describes the constraints and conceptual design of the H- injection system and its incorporation into the present PS2 lattice. The requirements for the special injection system elements are described, in particular the injection chicane and painting magnet systems and the charge exchange foil. Some key performance aspects are investigated, including the stripping efficiency, expected emittance growth and beam loss arising from the simulated number of multiple foil traversals, together with estimates of foil heating. | ||
| THPP088 | Design Considerations for the PS2 Beam Dumps | 3569 |
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| Studies have been made to evaluate and differentiate necessary beam disposal functions for the proposed PS2 accelerator. The paper describes briefly the different beam dump functionalities required for the PS2 machine and its transfer lines, and makes some first estimates about the expected beam loads. This data has been taken as input for comparing the different technical options for the dump systems, in particular to simulate the radiological impact of different internal or external beam dump concepts. The numbers derived have been used to help in evaluating the feasibility of the technical alternatives. | ||
| THPP089 | Gamma Transition Jump for PS2 | 3572 |
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| The PS2, which is proposed as a replacement for the existing ~50-year old PS accelerator, is presently considered to be a normal conducting synchrotron with an injection kinetic energy of 4 GeV and a maximum energy of 50 GeV. One of the possible lattices (FODO option) foresees crossing of transition energy near 10 GeV. Since many intensity dependent effects can take place in both the longitudinal and the transverse planes a fast jump of gamma transition is necessary in order to pass the non-adiabatic region rapidly. The aim of the present paper is on the one hand to scale the gamma transition jump, used since 1973 in the PS, to the projected PS2 and on the other hand based on these results the analysis of the implementation and feasibility of a gamma transition jump scheme in a conventional FODO lattice. | ||
| THPP090 | Beam Injection and Extraction of SCENT300, A Superconducting Cyclotron for Hadrontherapy | 3575 |
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||
| SCENT300 is a superconducting cyclotron able to deliver proton and carbon beam at 260 and 300 AMeV respectively. The simulations of the beam injection through the central region, the beam extraction through the electrostatic deflector for Carbon beam and by stripper foil for the proton beam are here presented. | ||
| THPP091 | One Nano-second Bunch Compressor for High Intense Proton Beam | 3578 |
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||
|
About ten bunches of 2MeV proton rf-linac with an average current of 150mA at 175 MHz will be deflected by kicker on different paths into a magnetic bending system. Passing this optimized geometry they approach each other longitudinaly (βλ = 0.114m) and arrive at the same time at the focus of the dipole system. For longitudinal focussing of the merged bunches a rebuncher cavity is included in the bending system. The motivation and the layout of the whole project, "Frankfurter Neutronen Quelle am Stern-Gerlach Zentrum" (FRANZ), were presented in details in previous conferences*,**. More accurate investigation results in a revision of the preliminary concept. For a theoretical proof of principle one trajectory with the biggest path length of a new geometry is calculated by a multi particle beam dynamics program (LORASR). Preliminary investigations showed, that magnetic fringing fields and bunch-bunch interactions have to be included as detailed as posible in the beam simulations. In this paper the beam dynamics results from LORASR-simulations, the new geometry and the code development for the bunch compressor are discussed in details.
*L. P. Chau et al. Proc. of the Eur. Part. Acc. Conf., Edinburgh (2006), 1690-1692. |
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| THPP093 | Conceptual Design of the PEFP Beam Line | 3581 |
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||
| In the Proton Engineering Frontier Project (PEFP), 20MeV and 100MeV proton beams from a 100MeV proton liner accelerator will be supplied to users for proton beam applications. Switch magnets will share the beam to three directions, two fixed beam lines and one AC magnet. The two fixed beam lines will be used for isotope production and power semiconductor production. An AC magnet will distribute the beams to three targets simultaneously. To provide flexibilities of irradiation conditions for users from many application fields, we designed beam lines to the targets with wide or focused, external or in-vacuum, and horizontal or vertical beams. As far as possible we designed the simple beam lines to reduce the construction cost. The details of the beam line conceptual design will be reported. | ||
| THPP094 | The Development of a Fast Beam Chopper for Next Generation High Power Proton Drivers | 3584 |
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||
|
The Front End Test Stand (FETS) project at RAL will test a fast beam chopper, designed to address the requirements of high-power proton drivers for next generation pulsed spallation sources and neutrino factories. The RAL ‘Fast-Slow’ chopping scheme for the 2.5 MeV, 280 MHz, ESS Medium Energy Drift Space (MEBT)* is evolving to address the requirements of the 3.0 MeV, 324 MHz, FETS project. The recent adoption of a more efficient optical design for the FETS MEBT** will result in a useful increase in beam aperture and permit an important reduction in the amplitude of the chopper E-fields. A description is given of a 'state of the art' high voltage pulse generator designed to address the FETS 'Slow' chopper requirement. Measurements of output waveform and timing stability are presented.
*M. Clarke-Gayther, "A Fast Beam Chopper for Next Generation High Power Proton Drivers," EPAC04. |
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| THPP096 | Injection Optimisation on the ISIS Synchrotron | 3587 |
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||
| The ISIS Facility at the Rutherford Appleton Laboratory in the UK produces intense neutron and muon beams for condensed matter research. At its core is a 50 Hz proton synchrotron which, as the commissioning of a new dual harmonic RF system concludes, can accelerate 3.75·1013 protons per pulse from 70 to 800 MeV, delivering a mean beam power of 0.24 MW. The multi-turn charge-exchange injection process strongly affects transverse beam distributions, space charge forces and beam loss, which ultimately limits operational intensity. The evolution of longitudinal distributions and subsequent trapping efficiency is also intimately linked with injection. Optimising injection is therefore a key consideration for present and future upgrades. This paper summarises injection studies including 2D space-charge simulations of the ISIS injection process using the ORBIT code. Comparisons of simulation results with measurements for a range of beam intensities are presented and an assessment is made of a correlated painting scheme in contrast to the usual anti-correlated configuration. | ||
| THPP097 | Commissioning Results of the Kicker Magnet in J-PARC RCS | 3590 |
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||
| Installation of the kickers in the extraction section of the RCS in J-PARC facility was completed. And they succeeded to extract the 3GeV proton beams in the first beam test. The operation parameters of the kickers agreed well with the parameters which were estimated from the magnetic field measurement and the current test of the power supplys. In this report, we summarized the results of the excitation test and the commissioning of the kicker magnet. The results of the magnetic field measurement showed the good uniformity in the wide range of the aperture. The characteristic feature of each kicker power supply was also measured precisely. Although the rise time and jitter of the output pulse have some minor variation due to the different characteristics of the thyratrons, the degree of variation was acceptably small. Combining the results of the magnetic field measurements, the relation between the charging voltage and the magnetic field was obtained for each kicker. The accelerated beam was successfully extracted at the operation parameters which were obtained from the relationship. The measurements result which was obtained by using the beam is also reported. | ||
| THPP098 | Simulations on a Beam Transport System for the Frankfurt Funneling Experiment | 3593 |
|
||
| The goal of the Frankfurt Funneling Experiment is to multiply beam currents by mergeing two low energy ion beams. Our setup consists of two ion sources, a two beam RFQ accelerator, a multigap deflector and a beam diagnostics. Current work is the design of a new beam transport between RFQ accelerator and deflector and first simulations will be presented. | ||
| THPP100 | Development of New Ion Sources for the Frankfurt Funneling Experiment | 3596 |
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||
| Funneling is a method to increase beam currents in several stages. The Frankfurt Funneling Experiment is a prototype of such a stage. The experimental setup consists of two ion sources with electrostatic lens systems, a Two-Beam RFQ accelerator, a funneling deflector and a beam diagnostic system. The two beams are bunched and accelerated in a Two-Beam RFQ and the last parts of the RFQ electrodes achieve a 3d focus at the crossing point of the two beam axis. A funneling deflector combines the bunches to a common beam axis. The newly optimized ion sources are adapted to the front end bunching section. First results and measurements will be presented. | ||
| THPP101 | Investigation of Lifetime of the Electronics and the Fiber Optics inside the Niche and the Tunnel in the Slow Extraction Area of SIS100 | 3599 |
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||
| The loss of ions in the slow extraction area of the SIS100 accelerator project at FAIR can be dangerous for the electronic equipment and fiber optics situated inside the tunnel and niches around. During the slow extraction lost ions irradiate the yoke of the quadrupole magnets and collimator and produce a neutrons flux, which can damage or make single event upset at the electronic devices. Also fiber optic cores fade under the action of irradiation. In the current work the investigation of the dose distribution and neutron fluxes, as well as the calculation of the lifetime of the electronics and fiber optics in different places of the tunnel have been done. By using these results the design of the niches and shielding is planned. | ||
| THPP102 | Radiation Damage Studies for the Slow Extraction from SIS100 | 3602 |
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| During the slow extraction from SIS100 synchrotron 5% of the beam will hit the wires of the electrostatic septum and will be lost. These losses produce very high radiation damage to the superconducting quadrupole doublet situated downstream of the extraction point. These beam losses were simulated with the help of Fluka code for U28+ and Ne5+ beams. Non-zero cross-section and non-zero angular divergence were assumed for the lost beam, allowing distributed modeling of the slow extraction losses. The radiation damage to different layers of the superconducting quadrupole cables was calculated. The lifetime of the s.c. cables of the quadrupoles was found to be too short. Thus, alternative quadrupole designs with higher radiation tolerances were investigated: with stainless steel shielding of the s.c. cables and with a gap in the mid-plane between the s.c. cables. | ||
| THPP103 | Design of the Beam Extraction System of the New Heavy Ion Synchrotrons SIS100 and SIS300 at FAIR | 3605 |
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| The proton and heavy ion synchrotrons SIS100 and SIS300 are the heart of the new FAIR facility which is under construction on the site of the present GSI. All ions from protons to uranium will be accelerated up to a magnetic rigidity of 100 Tm and 300 Tm, respectively. The design of the beam extraction system of both synchrotrons is completed and will be presented in this paper. The extraction devices of both synchrotrons are situated in one common straight section and deflect the beam vertically. SIS100 has been optimized for fast extraction by means of a distributed fast bipolar kicker system. However, slow extraction over a few seconds is also foreseen. SIS300 has been optimized for slow extraction and may generate spills of up to 100s. The slow extraction channel combines horizontal deflection by an electrostatic septum in the first stage with vertical deflection by a Lambertson septum magnet and subsequent magnetic extraction septa in the second stage. An emergency beam dumping system could be integrated in the extraction system of both machines. | ||
| THPP104 | The High Energy Beam Transport System for FAIR | 3608 |
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| The High Energy Beam Transport System of FAIR, with a total length of more than 2350 m, forms a complex system connecting seven accelerator- and storage-rings, the experimental caves, beam dumps, stripping stations, the antiproton target and the Super-FRS. The variety of beams to be transported is considerable, ranging from slow extracted beams with long spills of up to 100 s to short intense bunches with lengths of a few nanoseconds and a momentum spread of up to ±1%. The range of beam intensity covers more than six orders of magnitude. The SIS100/300 rings are located 13.5 m under ground while the rest of the facility is essentially on ground level necessitating a 3-dimensional layout of the beam line system. Most of the beam transport system consists of normal conducting magnets. However, the SIS300 beam line system has to be built with superconducting magnets. Due to the large variety of beam parameters, a careful planning of the beam diagnostics system is important. The paper summarizes the design fundamentals and the current status of the system design. | ||
| THPP105 | Beam Commissioning Results of the RCS Injection and Extraction at J-PARC | 3611 |
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| The beam commissioning of J-PARC (Japan Proton Accelerator Research Complex) 3 GeV RCS (Rapid Cycling Synchrotron) has been started from the end of year 2007. As injection is in the very first stage, an accurate and well controlled beam at the injection strongly related to the other part of the RCS commissioning, including extraction where, an well extracted beam directly reflects the overall commissioning result. In this paper, the beam commissioning results of the RCS injection and extraction will be reported. | ||
| THPP106 | Neutrino Beam Line at J-PARC | 3614 |
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A neutrino beam line for the long baseline neutrino oscillation experiment T2K is under construction at J-PARC in Tokai. Construction is proceeding on schedule and commissioning of the beam line will start in April of 2009. Proton beams are injected from the main ring, then bent about 80 degrees using superconducting magnets directing the beam toward the Super-Kamiokande detector. Muon neutrinos are produced from pions produced at the target. Precise beam tuning is quite important in our beam line since the beam intensity is expected to be 750 kW and failure of the tuning system may cause damage to the beam line components. For this purpose, we install four types of beam monitors in the primary beam line:
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| THPP107 | Lifetime Comparisons of Single and Double Layered HBC-Foils using 3.2MeV Ne+ Ion Beam | 3617 |
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| The Japan-Proton Accelerator Research Complex (J-PARC) requires thick carbon stripper foils of 300-500 μg/cm2 thick to strip electrons from the H-beam supplied by the linac before injection into the RCS. The energy depositions upon foil by the intense circulating proton bunched beam as well as H-beam result in the foil temperature of ~1800K. Thus, conventional carbon stripper foils will rupture in a very short time and even a high quality diamond foil will be broken at around 1800 K. Therfore, thick carbon stripper foils with high durability even at 1800K are indispensable for such accelerators. We have developed HBC (Hybrid type Boron mixed Carbon)-foil. We have measured the lifetime of a double and single-layered HBC-foils, diamond (DM) foils and commercially available carbon (CM) foils for comparisons using 3.2 MeV Ne+ ion beam, in which a significant amount of energy loss is deposited in the foils. The lifetime of the double-layered HBC- foil (180 μg/cm2 x 2) was found to be long 18 and 446 times longer than those of DM-foil (360μg/cm2 x 1) and double-layered CM foils ( 207μg/cm2 x 2), respectively. | ||
| THPP108 | Temperature Measurements of Carbon Stripper Foil by Pulsed 650keV H- Ion Beam | 3620 |
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| Thick carbon foils (>300 mg/cm2) has been used for stripping of H- ion beam at the 3 GeV Rapid Cycling Synchrotron (3GeV-RCS) of the J-PARC. The carbon stripper foils with long lifetime against high temperature >1800 °K are strongly required. We have recently developed a new irradiation system for lifetime measurement using the KEK 650keV Cockcroft-Walton accelerator with high current pulsed and dc H- beams, which can simulate the high-energy deposition upon foils in the RCS. The experimental results from the measured temperature of carbon stripper foil by the pulsed 650keV H- ion beam (-6mApeak, 0.3ms, 25Hz) and the observed time structure in the beam spot by a photo-transistor are described. | ||
| THPP111 | A 250 kHz Chopper for Low Energy High Intensity Proton Beams | 3623 |
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| A neutron pulse with 1 ns pulse length and a repetition rate of 250 kHz is needed for the experiments on nuclear astrophysics using the Frankfurter Neutron source at the Stern-Gerlach-Zentrum. The time structure of the neutron flux is given by the primary proton beam witch hits a 7Li target. The creation of the required time structure on an intense proton beam of 200 mA dc with respect to emittance growth and beam losses is demanding. The pulsing of the ion source depends on the rise time of the plasma whereas the pulsing of the extraction voltage leads into high power deposition into the multi aperture extraction system. On the other hand a chopper system downstream of the RFQ results in rf power consumption due to beam loading and the problem of beam dumping at a beam power of several kW. Therefore it is planed to install a chopper as part of a resonant circuit in the LEBT – section consisting of four solenoids. Two different methods, magnetic and electric deflection, will be discussed with respect to emittance growth, beam losses and the influence on space charge compensation processes. Numerical simulations and preliminary results of experiments will be presented and compared. | ||
| THPP112 | Leakage Field of Septum Magnets of 3 GeV RCS at J-PARC | 3626 |
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| Septum magnets are installed in RCS (Rapid cycling Synchrotron) at J-PARC for the beam injection and extraction. In order to realize MW beam in the RCS ring and reduce the beam loss during the beam injection and extraction, the septum magnets have large physical aperture and are operated in DC. Thus there are high magnetic fields in the gaps during the acceleration, but the leakage fields are nevertheless suppressed down to a few Gauss to suppress the closed orbit distortion. In order to reduce the magnetic leakage field from the septa at beam orbit in the RCS ring, the silicon steel sheets are set for magnetic shield. In addition a few ring vacuum chambers are made by the magnetic stainless steel. Up to now, the development and field measurement of the septum magnets has been finished, and the beam commissioning of the RCS are carried out. In this presentation, the field measurements of the septum magnets are summarized and the influences of the leakage field upon the beam orbit are reported. | ||
| THPP113 | Emittance Growth at LHC Injection from SPS and LHC Kicker Ripple | 3629 |
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| Fast pulsed kicker magnets are used to extract beams from the SPS and inject them into the LHC. The kickers exhibit time-varying structure in the pulse shape which translates into small offsets with respect to the closed orbit at LHC injection. The LHC damper systems will be used to damp out the resulting betatron oscillations, to keep the growth in the transverse emittance within specification. This paper describes the results of the measurements of the kicker ripple for the two systems, both in the laboratory and with beam, and presents the simulated performance of the transverse damper in terms of beam emittance growth. The implications for LHC operation are discussed. | ||
| THPP114 | LHC Transverse Feedback Damping Efficiency | 3632 |
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| A simulation model has been developed to predict the damping efficiency of the LHC transverse feedback system in the presence of coupled bunch instabilities and under realistic assumptions for the injection error. The model tracks both the centre of gravity of a bunch and the r.m.s beam size during and after injection. It includes the frequency characteristic of the transverse feedback system. Nonlinearities in the beam optics will cause the bunches to filament and lead to an increase of the transverse emittance after injection. The resistive wall instability reduces the effectiveness of the transverse feedback by slowing down the damping process. Possibilities for enhancing the performance of the feedback system by signal processing schemes are outlined. | ||
| THPP115 | The Proposed ISAC-III Upgrade at TRIUMF | 3635 |
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| Presently, the ISAC facility produces radioactive ions by a single driver beam of up to 100microA of 500MeV protons (50kW) impinging on either of two production targets which are configured such that only one radioactive ion beam (RIB) is available for use at any one time; and the experimental hours are shared between several facilities in the low energy and two accelerated beam experimental areas. The ISAC-III upgrade is proposed to increase the number of RIBs simultaneously available to three. The upgrade involves the addition of a high power electron linac, 50MeV/10mA, that would irradiate one of two new independent targets and produce RIBs through photo-fission. A second beamline from the existing cyclotron would deliver an additional 500MeV 200microA proton beam to the new target area to irradiate the second target producing the third simultaneous beam. The proposal includes an additional post-accelerator front-end to augment the existing infrastructure to provide the capability of accelerating two of the RIBs simultaneously. The paper summarizes the upgrade and discusses design choices to optimize nuclide availability across the three experimental areas. | ||
| THPP120 | Measurements on an A/D Interface Used in the Power Supply Control System of the Main Dipoles of CNAO | 3638 |
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| The CNAO (the Italian Centre of Oncological Hadrontherapy, near Pavia) is in its final step of construction and is about to be fully operative. It is based on a synchrotron that can accelerate protons up to 250MeV and carbon ions up to 400MeV/u for the treatment of patients. In this paper we describe an A/D interface, used in the power supply control system of the synchrotron main dipoles, called B-Train. The field is measured in a dedicated dipole connected in series with the sixteen ones of the synchrotron and is then fed back to the power supply. The field is obtained integrating and digitizing the voltage induced on a pickup coil inserted in the gap of the seventeenth dipole. The A/D interface under study is based on a 64-channel current to frequency converter ASIC, in CMOS 0.35 μm technology, followed by a counter and uses a recycling integrator technique. The digital signal obtained is then used to generate a feedback signal for control system of the dipoles power supply. We present the electronic structure, the lab measurements and the behavior for various setups of the A/D interface described. | ||
| THPP121 | The SSRF Storage Ring Dipole and Sextupole Magnet Power Supplies | 3641 |
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| SSRF is a third generation synchrotron radiation light source. It has a full energy injection storage ring of 3.5GeV. The storage ring dipole magnet string and sextupole magnets strings are powered by 10 large magnet power supplies. The power supply output current ranges from 250A to 800A, and the output voltage ranges from 140V to 840V. These power supplies are digital controlled, with bridge topology, and diode rectifiers with step-down transformers. In this paper, the commissioning results of these power supplies are presented, together with the circuit topology and the control schemes. | ||
| THPP122 | Fast High-Power Power Supply for Scanning Magnets of CNAO Accelerator | 3643 |
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| The paper presents the design aspects and performance measurements of the CNAO Scanning Magnets’ power supply (PS) rated ±550A/±660V and developed in collaboration between OCEM SpA and INFN-CNAO. CNAO is a medical synchrotron producing carbon ions and protons for the cure of deep tumours. The Scanning Magnets are dipole magnets used to move the beam in an x-y plane at the very end of the beam extraction line. The PS current will be set in order to cover the targeted tumour area. To accomplish such a task the specifications of the PS are very stringent: current ramp speed is required to be as fast as 100 kA/s with an overall precision class of 100 ppm. Moreover the wide (20x20 cm2) area to be covered by the beam requires a wide current range. High voltage peaks are required during transients whereas low voltage is needed during steady state. The above characteristics are challenging design issues both with respect to topology and control optimization. | ||
| THPP123 | Ramping Power Supplies for the SSRF Booster | 3646 |
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| The SSRF booster magnetic field ramped with a 250ms ramp, 2Hz cycle rate, and biased quasi-sinusoidal wave shape is successfully realized. Two Digital Switch-mode Power Supplies (DSPS) separately deliver currents to all dipoles, and other four DSPS deliver to the quadrupoles and sextupoles in families. Tracking precision and reducing line power fluctuation requirements are particularly challenging because of the fast ramp and high inductance load. In order to meet the requirements, the magnetic energy recycle, digital regulation and novel PID correction circuit are used. On Oct. 5th 2007, after a few days commissioning of the SSRF booster, the beam was boosted up to 3.5GeV firstly in SSRF, it proved that the design of ramping power supplies was correct and the manufacture was successful. The power supply system and its performance are described in this paper. | ||
| THPP124 | Commissioning of the 150 MeV SSRF Linac | 3649 |
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| The 150 MeV SSRF linac has been integrated and commissioned from late 2006 to middle of 2007. This paper presents the design, installation, commissioning and status of this linac. | ||
| THPP125 | Performance Evaluation of the Switching Mode AC Power Supply | 3652 |
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| In order to improve the injection efficiency, the output current waveform of the AC power supplies must be great. Therefore, to ensure smooth and efficient injection of the booster ring, the phase jitter of the AC power supplies current must be less than ±4ns. A new AC power supply is constructed and employ IGBT modules operating at higher switching frequency than the old GTO-based system for the dipole magnet. This new power supply will not only improve the phase jitter but also increase the operating efficiency than the old power supply. The measured dynamic range of the of the 10 Hz sine wave current output is better than 75dB and phase jitter is less than ±4ns. The improved performance evaluation is illustrated in the paper. | ||
| THPP126 | Four Quadrant 60 A, 8 V Power Converters for LHC | 3655 |
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| The LHC (Large Hadron Collider) particle accelerator requires many true bipolar power converters (752), located under the accelerator dipole magnets in a radioactive environment. A special design and topology is required to obtain the necessary performance while meeting the criteria of radiation tolerance and compact size. This paper describes the ±60A ±8V power converter, designed by CERN to meet these requirements. Design aspects, performances and test results of this converter are presented. | ||
| THPP127 | ATF2 High Availability Power Supplies | 3658 |
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| ATF2 is an accelerator test facility modeled after the final focus beamline envisioned for the ILC. By the end of 2008, KEK plans to commission the ATF2. SLAC and OCEM collaborated on the design of 38 power systems for beamline magnets. The systems range in output power from 1.5 kW to 6 kW. Since high availability is essential for the success of the ILC, Collaborators employed an N+1 modular approach, allowing for redundancy and the use of a single power module rating. This approach increases the availability of the power systems. Common power modules reduces inventory and eases maintenance. Current stability requirements are as tight as 10 ppm. A novel, SLAC-designed 20-bit Ethernet Power Supply Controller provides the required precision current regulation. In this paper, Collaborators present the power system design, the expected reliability, fault immunity features, and the methods for satisfying the control and monitoring challenges. Presented are test results and the status of the power systems. | ||
| THPP128 | Failure Mechanisms of Power Systems in Particle Accelerator Environments and Strategies for Prevention | 3661 |
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| This paper discusses the mechanisms that cause degradation and failure in DC-DC converters destined for high radiation and magnetic field environments, particularly those encountered in accelerators. Failure mechanisms discussed include transformer saturation, loss of PWM control, and power supply turn-off. Degradation mechanisms that produce circuit performance outages include circuit parameter drift in Mosfets due to temperature and Vgsth reduction. Environmentally induced drift of current limit, voltage references, and switching performance are also presented. The author’s background in worst case analysis of Space based power supplies gives them particular insight into the radiation impact, assessment, and mitigation of such phenomenon. A variety of techniques for identifying and reducing the probability of these failures are presented. Methods include analysis based strategies, modified switching timing and control, improved gate drive circuitry, proper component selection, and appropriate shielding. Results are provided for a 3kW supply developed for the LHC at CERN using COTS in an 45kRAD TID, 7.7·1012 neutron fluence, and 300 Gauss magnetic field environment. | ||
| THPP129 | New Generation of AD-measurement Cards for High Accuracy Measurements | 3664 |
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| Current transducers, together with the AD conversion of the measured current, are the key elements of high precision power supplies. The accuracy of commercially available current transducers is within the range of a few ppm. Any degradation of this precision by the succeeding stages must be kept as small as possible. Therefore, the accuracy of the AD conversion has to be at least in the same order of magnitude. The presented AD-measurement card improves the accuracy of the available, already calibrated precise ADCs by correcting the remaining errors. The necessary accuracy can only be achieved by measuring and correcting the miscellaneous errors of ADC and involved components, like voltage reference, antialiasing filter and input amplifier. From the measured deviation a correction look-up table is derived and later processed. Other implemented means for the improvement of the precision are the stabilization of the temperature, minimization of the electromagnetic influence by galvanic isolation, reduction of electrical noise and a fully differential signal path. | ||
| THPP130 | SSRF Magnet Power Supply System | 3667 |
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| The Shanghai Synchrotron Radiation Facility (SSRF) is a third-generation synchrotron radiation light source. In SSRF, there are 520 sets of magnet power supplies for the storage ring and 163 sets for injector. All of the power supplies are in PWM switched mode with IGBT. A high precision stable output power supply for 40 dipoles rated at 840A/800V with the stability of ±2·10-5/8hrs is used for the storage ring. 200 sets of chopper type power supplies are used for exciting main winding of quadrupoles independently. In the booster, two sets of dynamic power supplies for dipoles and two sets for quadrupoles run at the biased 2Hz quasi-sinusoidal wave. All above power supplies work with digital power supply controllers designed by either PSI or SINAP. All power supplies are manufactured at professional power supply companies in China. | ||
| THPP132 | Review of the Initial Phases of the LHC Power Converter Commissioning | 3670 |
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| The LHC requires more than 1700 power converter systems that supply between 60A and 12kA of precisely regulated current to the superconducting magnets. For the first time at CERN these converters have been installed underground in close proximity to many other accelerator systems. In addition to the power converters themselves, many utilities such as air and water cooling, electrical power, communication networks and magnet safety systems needed to be installed and commissioned as a single system. Due to the complexity of installing and commissioning such a large infrastructure, with inevitable interaction between the different systems, a three phase test strategy was developed. The first phase comprised the manufacture, integration and reception tests of all converter sub-systems necessary for powering. The second phase covered the commissioning of all the power converters installed in their final environment with the utilities. The third phase will add the superconducting magnets and will not be covered by this paper. The planning and execution that have led to the successful completion of these initial phases are described. Results and conclusions of the testing are presented. | ||
| THPP133 | Magnet Power Converters for the New Elettra Full Energy Injector | 3673 |
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| A large number of power converters has been required to supply the coils and the magnets of the four sub-structures of the new Elettra full energy injector. The Linac, and the two transfer lines require highly stabilized DC power converters while the Booster has to be operated at 3 Hz supplying the magnets with sinusoidal current waveforms. The extraction Bumpers require slow pulse supplies. In order to keep all output voltages below 1 kV, a special connection has been adopted for the Booster dipoles. A particular type of low power four-quadrant converters with embedded Ethernet connection has been designed at Elettra for this specific project. The article will present the relevant facts about the different power converters and their performances. | ||
| THPP134 | Injection and Extraction DC Magnets Power Supplies for 3GeV Rapid Cycling Synchrotron of J-PARC | 3676 |
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Proton beams have been successfully accelerated to the design energy of 3 GeV in the RCS at the J-PARC*. In the injection, dump and extraction sections of the RCS, septum magnets, a quadrupole magnet, dc kicker magnets and steering magnets have been installed and operated at DC. For the septum magnets, there is little space area available for the septum coil and a magnetic shield**. Therefore the power supplies are required high excitation current. Maximum currents of the injection and dump septum magnets are less than 7 kA. The extraction septum magnets need the maximum current of 12 kA***. For saving the cost and the installation space of the extraction septum magnets power supplies, a main power supply, which excites three extraction septum magnets in series, and three auxiliary power supplies for adjusting the current to the each magnet are employed. Long-term stability and the current ripples are required to be less than the order of 100 ppm for those power supplies in order to provide the required acceptance for the beams. This presentation shows design and measurements of the the injection and extraction DC power supplies.
*JAERI Technical Report 2003-044 and KEK Report 2002-13. |
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| THPP136 | The Replacement of the Isis White-circuit Choke | 3679 |
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ISIS, located at the Rutherford Appleton Laboratory is the world’s leading pulsed neutron source. It produces intense bursts of neutrons every 20mS when 800MeV protons are fired into a heavy metal target by an accelerating synchrotron. The ISIS synchrotron is based on a resonant “White Circuit”* allowing superimposed DC and AC currents to circulate in the ring of dipole and quadrupole magnets. The magnets themselves resonate with tuned capacitor banks at 50Hz and a large ten-winding choke allows both a path for the DC component of the current and a means to inject the AC power which maintains the 50Hz AC oscillation. This choke, which dates from the 1960’s, was a veteran of the “NINA” synchrotron in Daresbury before it began service at ISIS. Should it fail it could take at years to repair and a scheme is now well under way to replace it with ten individual chokes with in-situ spares so that the system will gain redundancy and robustness. This paper covers progress to date and the problems that have been encountered and their solutions.
*M. G. White et al. "A 3-BeV High Intensity Proton Synchrotron," The Princeton-Pennsylvania Accelerator, CERN Symp.1956 Proc., p525. |
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| THPP137 | Development of Vacuum Components for XFEL/SPring-8 | 3682 |
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| Several new vacuum components have been developed for the XFEL/SPring-8 project. Vacuum waveguide flanges for C-band and S-band were successfully developed. These flanges provide both RF seal and vacuum seal. This seal mechanism can make vacuum seal even with a scratched gasket. A solid-lubricated clean bolt was developed for C-band and S-band flanges to avoid organic dust pollution that induce multipactor. New vacuum flange for accelerator beam line can use three types of gasket. A small RF contact for 28 mm inside diameter bellows was developed. This unfixed RF contact can move freely in all directions and displaced large. | ||
| THPP138 | Achievement and Evaluation of the Beam Vacuum Performance of the LHC Long Straight Sections | 3685 |
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| The bake-out and activation of the 6 km Long Straight Sections (LSS) of the Large Hadron Collider (LHC) is in its final step. After bake-out and activation of the NEG coating, the average ultimate pressure, over more than one hundred vacuum sectors, is below 10-11 mbar. Therefore, the nominal requirement for the four experimental insertions is guaranteed. The nominal performances are also ensured for all the other insertions where collimators, RF cavities and beam dumping systems are present. The main difficulties encountered during the bake-out and activation of NEG coated chambers of the LSS vacuum sectors will be presented and discussed. In particular, the acceptance test and the limiting factors of the reached ultimate pressures will be addressed. Furthermore, the influence on the ultimate pressures of the beam vacuum elements (collimators, beam instrumentation, etc.) will be discussed. Finally, preliminary results obtained from a laboratory NEG pilot sector dedicated to the quality control of the LHC beam vacuum and to the evaluation of the NEG performance will be presented. | ||
| THPP139 | Stainless Steel Vacuum Chambers for the SSRF Storage Ring | 3688 |
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| Stainless steel 316LN plate was adopted as main material for SSRF storage ring vacuum chambers and ante-chamber structure was used just as other 3rd light source. The analysis for the deformation of the chambers under atmospheric pressure and the thermal situation under synchrotron radiation were done with ANASYS program. Many problems on the structure design and fabrication technique were revealed and suitable solving methods were found in the process of development and manufacture of nine chamber prototypes. Deep draw die was used to form the chambers’ figuration. Wire cutting and CNC machining were used to manufacture the main components. The flatness tolerance, straightness tolerance and the deformation of the chambers under atmospheric pressure were all less than 1mm. After annealed in the vacuum furnace at 850℃, the magnetic permeability of welding seal was reduced from 2.5 to 1.02, the residual stress was deleted, and the vacuum performance was improved. Now SSRF vacuum system is being operated very well. The average pressure without beam is about 2.5×10-8 Pa and the average pressure with beam of 3GeV/100mA is about 8×10-7 Pa. | ||
| THPP140 | First Experience on NEG Coated Chambers at the Australian Synchrotron Light Source | 3690 |
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| The Australian Synchrotron, a 3 GeV third generation Light Source saw its first light in 2006. At full capacity it will house more than 30 photon beam lines providing state of the art facilities to support fundamental and applied research to the Australian scientific community. In the regional context, the Australian Synchrotron will also effectively complement the lower energy synchrotrons in Singapore (0,8 Gev) and Taiwan (1.5 GeV). The vacuum system of the storage ring, 216 m circumference, includes ion pumps and NEG cartridge pumps. Two NEG coated, ESRF style, aluminium Insertion Devices, each 2,5 m long, have been also installed in the storage ring to boost machine parameters and broaden the spectrum of wavelength available for experiments. Preliminary vacuum results obtained during conditioning and initial operation of the Insertion Devices are reported and compared to uncoated chambers. These results confirm the effectiveness of the NEG coating technology in reducing pressure build up inside conductance limited narrow chambers. Technological issues related to the chambers preparation, film deposition, quality control and characterization will be also discussed. | ||
| THPP141 | Test of a NEG Coated Copper Dipole Vacuum Chamber | 3693 |
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| The paper reports about a test carried out at the 1.5 GeV storage ring MAX II where a standard dipole chamber made of stainless steel was replaced by a NEG coated chamber made of copper. The standard MAX II stainless steel dipole vacuum chamber is connected to an ion pump and a sublimation pump while the NEG-coated copper dipole vacuum chamber has no additional pumps. The NEG-coated dipole chamber made of copper has been demonstrated to work well with a stable vacuum level in the region where it is installed. The coating procedure for the bent dipole chamber copper tube is slightly more complicated than the coating procedure for a straight chamber of similar size due to its curvature and lack of line-of-sight. The procedure is also described in some detail. The main motivation for the interest in NEG-coated vacuum tubes is the reduced cost of the vacuum system and also the possibility to build more slender vacuum systems, thus simplifying and optimizing the design of accelerator magnet systems. | ||
| THPP142 | Vacuum Conditioning of the SOLEIL Storage Ring with Extensive Use of NEG Coating | 3696 |
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| The vacuum system of the SOLEIL storage ring is designed using a combination of standard pumps like Sputter Ion Pumps and Titanium Sublimation Pumps (TSP) and Non Evaporable Getter (NEG) coating. Following the ESRF results on low gap insertion device (ID) chambers, it was decided to use, in addition to the traditional pumps, NEG coating deposited by magnetron sputtering on extruded aluminium vessels. This has been applied in an extensive way to all the straight vessels of the storage ring that means quadrupole vessels and ID vessels, which represent about 56% of the circumference. The starting configuration of the SOLEIL vacuum system included all the NEG coated low gap ID chambers among which a 10.5 m long chamber. Conditioning of the vacuum system over an integrated beam dose of 500 A.h will be presented. The periodical re-activations of the TSP performed early 2007 improved significantly the conditioning rate. A comparison of the vacuum behaviour of two similar cells one with NEG coating and traditional pumping versus one with only NEG coating demonstrates the ability of the NEG coating to keep alone the pressure at low level. | ||
| THPP143 | Vacuum Design of the TPS Relates to the Beam Effects | 3699 |
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| The concept of the vacuum design for the 3 GeV Taiwan Photon Source (TPS) considers several points of view which relates to the beam effects. The vacuum design of the low outgassing rate and the effective pumping configurations to obtain the lowest average pressure in the electron storage ring is to obtain the longer beam life time and the least of the ion trapping effect and the consequent problem of beam ion instability. The inner structure of the beam ducts provides the lower impedance which reduces the problems of the collective beam instability and the heating dissipation and damage to the vacuum components. The thin wall of the beam ducts and the bellows are designed for the sextupoles that offers the function of fast feedback orbit correction of the beam. The final performance of the third generation light source with low emittance will rely on the original design of vacuum systems for the electron beam. The design philosophy of the vacuum systems for the TPS will be described. | ||
| THPP144 | The Vacuum System for SSRF Storage Ring | 3702 |
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| The vacuum system for SSRF was completed at the end of 2007 and has run for one month without any malfunction. The vacuum chamber for the storage ring made from stainless steel 316LN plate. About 180 absorbers and 80 RF bellows with a single finger structure are used for the storage ring. About 292 compound pumps (SIP+NEG) and 188 TSP are used. After the vacuum system in the straight section of a cell and all pumps in the bending section were baked, the ultimate pressure reached 2×10－8 Pa. Normally, the temperature raise on the chambers any where is less than 4℃ with current 100mA. The temperature raise of the cooling water for all absorbers is less than 3℃. The vacuum control and interlock system are on working order. | ||
| THPP145 | Machine Operation Issues Related to the Vacuum System of the ESRF | 3705 |
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| This paper deals with various operational issues related to the vacuum system of the ESRF storage ring. The impact on the vacuum pressure, beam lifetime, beam losses and other machine parameters after installation of new chambers, diagnostics, RF cavities and insertion devices, and vacuum leaks is discussed in some detail. Particular emphasis is given to the behaviour of the prototype of a 2m-long cryogenic in-vacuum undulator, a new RF cavity, and NEG-coated chambers. Lessons learned from the operation of these and other vacuum components will be extended to the proposed machine upgrade. | ||
| THPP146 | High-voltage Power Supply Distribution System | 3708 |
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| High-voltage splitters enable connecting a larger number of ion-pumps to a single ion-pump controller. In particle accelerator facilities where relatively small pumps are used, using high-voltage splitters can significantly reduce costs and rack space. By using simple high-voltage splitters some functionality of the conrollers can be lost. The presented high-volage splitter is one of the most advanced devices on the market. It measures current going to every pump in the range 100 pA to 100 mA with an accuracy of 5%. Fully configurable tables are used to convert the measured current to the pressure at the pump. Current measurements are also used to monitor cable and ion-pump aging which results in linear increase of current with time. Hardware interlocks are used to disconnect individual pumps in case of poor vacuum to avoid pump damage. The limits can be set by the user, who can also set the number of active pumps. EPICS support was developed for the device with graphical user interfaces writen in EDM, java and WebCA. Since the presented device covers or exceeds a lot of the ion-pump controller functionality, simpler controlers can be used. | ||
| THPP147 | NEG Coated Chambers at SOLEIL: Technological Issues and Experimental Results | 3711 |
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| The SOLEIL accelerator complex includes a 100 MeV LINAC pre-injector, a full energy booster synchrotron and a 2.75 GeV electron storage ring with a 354-meter circumference, which provides synchrotron light to 24 photon beam lines. SOLEIL is the first synchrotron facility specifically designed to make extensive use of Non Evaporable Getter (NEG) coating technology to improve the vacuum, reduce bremsstralhung radiation and boost beam performances. In fact, NEG coating of the straight parts of the vacuum system covers more than 50% of the overall storage ring surface and includes 110 quadrupole and sextupole chambers as well as several conductance limited narrow insertion devices. Use of such a large amount of NEG coated chambers has posed several challenges in term of coating technology, chamber testing, installation and machine commissioning. We report in the present paper main technological issues related to the chambers preparation, film deposition, quality control and characterization. Chambers installation in the main ring, conditioning and activation procedures as well as preliminary vacuum performances will be also discussed. | ||
| THPP148 | Implementation of the SSRF Vacuum Control System | 3714 |
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| The Shanghai Synchrotron Radiation Facility (SSRF) is a third generation light source consisting of a 150MeV linac, a full energy booster and a 3.5GeV storage ring. The vacuum control system is a standard hierarchical control system based on EPICS. Serial device servers are used to connect most of vacuum devices such as gauge controllers, pump power supplies to the control network directly and integrated with EPICS using soft IOC. Ethernet based PLC systems are adopted for the valves control, temperature monitor, etc. The soft IOCs are running on the rack servers and the VLAN is used for separate to the other systems. An enhanced distributed archive engine stores runtime data to centre database that using native XML data type with XML schema for data storage. It is a high performance system and running well for daily operation now. | ||
| THPP150 | LANSCE Vacuum System Refurbishment Plan and Vacuum Alert System Improvements for Predictive Maintenance | 3717 |
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| The Los Alamos Neutron Science Center (LANSCE) accelerator, an 800-MeV H+/H- LINAC with a storage ring, has been operated over 30 years since early 1970s. A refurbishment project named LANSCE-R was approved and started in 2007. This paper describes our plan for vacuum system refurbishment as well as an update on the ongoing vacuum email alert system improvement project, which will eventually notify workers of the need for predictive maintenance of particular devices like ion pumps. | ||
| THPP151 | Feasibility Study for High Performance Vacuum Chamber | 3720 |
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| For longer beam lifetime, many synchrotron light sources employ ante-chamber type of beam ducts to reduce photon- and electron-stimulated desorption gases around stored beams. Still more reduction, however, can be expected if an X-ray transparent membrane, such as Beryllium thin film, is installed between the beam chamber and the ante-chamber because X-rays from stored beams pass through the membrane while gas molecules desorbed in the ante-chamber are shut out by the membrane. Similarly, photoelectrons and secondary electrons traveling from the ante-chamber to the beam chamber are also shut out by the membrane; this function is expected to mitigate beam-photoelectron instability in positron storage rings. Feasibility study for this type of vacuum chamber has been started at PF, and the result of the first-stage experiment will be presented. |