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| WEPMA001 | Proposed Linac Upgrade with a SLED Cavity at the Australian Synchrotron, SLSA | 2738 |
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| The Australian Synchrotron Light Source has been operating successfully since 2007 and in top-up mode since 2012 while gradually being upgraded to reach an excellent beam availability exceeding 99 %. Considering the ageing of the equipment, effort is required in order to maintain the reliability at this level. The proposed upgrade of the linac with a SLED cavity has been chosen to mitigate the risks of single point of failure and lack of spare parts. The linac is normally fed from two independent 35 MW pulsed klystrons to reach 100 MeV beam energy and can be operated in single (SBM) or multi-bunch mode (MBM). The SLED cavity upgrade will allow remote selection of single klystron operation in SMB and possibly limited MBM without degradation of beam energy and reduce down time in case of a klystron failure. The proposal for the SLED cavity upgrade is shown and the linac designs are detailed. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPMA001 | |
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| WEPMA002 | The Beam Chopper Power Converter for MedAustron: Safety by Design and Development | 2741 |
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| MedAustron is the Austrian centre for hadron therapy and non-clinical research. The beam chopper system is an essential component for patient safety in specific hazardous situations as well as for beam delivery from the synchrotron to the irradiation rooms. This paper presents the results from the development phase and the commissioning of the MedAustron beam chopper system. Details will be given on the design, the risk management, the test and the verification of the chopper power converter (PKC). | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPMA002 | |
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| WEPMA003 | Vacuum System Design for the Sirius Storage Ring | 2744 |
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| Sirius is a 3 GeV 4th-generation light source under construction by the Brazilian Synchrotron Light Laboratory (LNLS). Sirius will have a low emittance storage ring, 0.28 nm-rad, based on 20 cells of a highly compact lattice – 5-bend achromat (5BA). This lattice concept leaves very little space for components and therefore requires narrow vacuum chambers with tight mechanical tolerances. Most of the storage ring vacuum chambers will be made of OFS copper and have a circular cross section with inner diameter of 24 mm and a wall thickness of 1 mm. The unused synchrotron radiation will be distributed along the water cooled walls of the chambers. Due to the small conductance of the chambers, the vacuum pumping will be based on distributed concept and then non-evaporable getter (NEG) coating will be extensively used, with more than 95% of the chambers being coated. In this paper, we present an overview of the storage ring vacuum system and the main vacuum chambers fabrication developments. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPMA003 | |
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| WEPMA004 | A 250 Hz AC Scan Magnet for High-Power Radioisotope Production and BNCT Applications | 2747 |
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Funding: D-Pace acknowledges Canadian Government funding through SRED-CRA & NSERC-USRA, and through regional funding provided by KAST. This paper describes the proto-type magnet measurement results for a compact (212 mm, effective length) yet large gap (97 mm) ambient air-cooled laminated AC scan magnet. A large aperture is essential for machine safety in radioisotope production, and Boron Neutron Capture Therapy (BNCT) applications with steady-state beam power up to 50 kW *. Rose shim and Purcell filter techniques are examined for improved transverse field flatness. The measured magnetic field and frequency response curves through a range from (250 Gauss, 70 Hertz) to (25 Gauss, 250 Hertz) are given for the case of an air-gap, SS316 beampipe, and SS316 bellows. Measured transverse and longitudinal magnetic field curves are also given. A model of the frequency response of the magnet was created and validated. The model simplifies power supply selection and maps the effects of system natural frequency on the magnetic field. Tests were conducted with and without a capacitor in parallel with the magnet coils. Lastly, algorithms for flat-topped square, and circular scanned beam intensity distributions are given. * M.P. Dehnel et al, "A Specialized High-Power (50 kW) Proton Beamline for BNCT", Proc. of NA-PAC13, pp.116-118, Pasadena, CA, USA, Oct 2013. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPMA004 | |
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| WEPMA005 | Particularities of the ARIEL e-Linac Cryogenic System | 2750 |
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Funding: Canada Foundation for Innovation, British Columbia Knowledge Development Fund, and National Research Council Canada. The Advanced Rare IsotopE Laboratory (ARIEL) is a major expansion of the Isotope Separation and Acceleration (ISAC) facility at TRIUMF [1]. A key part of the ARIEL project is a 10 mA 50 MeV continuous-wave superconducting radiofrequency (SRF) electron linear accelerator (e-linac). The 1.3 GHz SRF cavities are cooled by liquid helium (LHe) at 2 K [2]. The 4 K 2 K LHe transition is achieved onboard of each cryomodule by the cryoinsert containing counterflow heat exchanger augmented with JT valve [3]. Air Liquide LHe cryoplant provides 4 K LHe to cryomodules. After successful commissioning of the cryoplant, 2 K sub-atmospheric (SA) system and cryomodules, the ultimate integration test confirmed stable operation of two cryomodules comprising two 9 cell SRF cavities. Particularities of this cryogenic system include conservative design of the oil removal system, original design heat exchanger in the SA pumping system, hermetic SA pumps, inline full SA flow purifier, multipurpose recovery/purification compressor, modular LHe distribution system, top-loaded design cryomodules, and overall radiation resistant design. The paper presents details of these features as well as integration tests results. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPMA005 | |
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| WEPMA007 | Experimental Study of Multipactor Suppression in Dielectric Materials | 2753 |
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| A novel coaxial resonator to investigate two-surface multipactor discharges on metal and dielectric surfaces in the gap region under vacuum conditions (~10-8 mbar) has been designed and tested. The resonator is ~ 100 mm in length with an outer diameter of ~ 60 mm (internal dimensions). A pulsed RF source delivers up to 30 W average power over a wide frequency range 650-900 MHz to the RF resonator. The incident and reflected RF signals are monitored by calibrated RF diodes. An electron probe provides temporal measurements of the multipacting electron current with respect to the RF pulses. In this paper we compare and contrast the results from the RF power tests of the alumina (97.6% Al2O3) and quartz samples without a coating, “the non-coated samples” and the Alumina and quartz samples with a thick TiN coating in order to evaluate a home made sputtered titanium nitride (TiN) thin layers as a Multipactor suppressor. The effectiveness of this method is presented and discussed in the paper. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPMA007 | |
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| WEPMA008 | RF Design of a High Gradient S-Band Travelling Wave Accelerating Structure for Thomx Linac | 2757 |
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| There is growing demand from the industrial and research communities for high gradient, compact RF accelerating structures. The Thomx high gradient structure (HGS) is travelling wave (TW), quasi constant gradient section and will operate at 2998.55 MHz (30°C in vacuum) in the 2π/3 mode. The optimization of the cell shape (Electromagnetic design) has been carried out with the codes HFSS and CST MWS, in order to improve the main RF characteristics of the cavity such as shunt impedance, accelerating gradient, group velocity, modified Poynting vector, surface fields, etc. Prototypes with a reduced number of cells have been designed. For an input power of about 20 MW, EM simulation results show that an average accelerating gradient of 28 MV/m is achieved which corresponds to a peak accelerating gradient of 35 MV/m, a peak surface gradient of 44 MV/m and peak modified Poynting vector Scmax of 0.24 MW/mm2. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPMA008 | |
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| WEPMA009 | 3 GHz Single Cell Cavity Optimization Design | 2761 |
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In order to develop a high gradient S-band electron accelerating structure, an optimized travelling wave (TW) single-cell cavity operating at the frequency of 3 GHz with 2π/3 phase advance, is proposed. Starting from the well-known accelerating cells design developed by the Laboratoire de l'Accélérateur Linéaire (LAL) and the Stanford Linear Accelerator Centre (SLAC), for linear accelerators; it is possible to improve the main RF parameters, such as quality factor, shunt impedance, enhancement factor and group velocity, by choosing a suitable shape of the inner surface. Even though surface electric field is being considered as the only main quantity limiting the accelerating gradient; the importance of power flow and the modified Poynting vector*, has been highlighted from high-gradient experimental data. In this context, the new field quantity (Sc) is derived from a model describing the RF breakdown trigger phenomenon wherein field emission currents from potential breakdown sites produce local pulsed heating. In particular, the modified Poynting vector takes into account both active and reactive power flow travelling along the structure. The main results presented in this paper have been carried out with the 3D electromagnetic simulation codes: High Frequency Structural Simulator solver (HFSS) and CST MICROWAVE STUDIO (CST MWS).
* A. Grudiev et al., "New local field quantity describing the high gradient limit of accelerating structures", PRST:AB 12, 102001 (2009). |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPMA009 | |
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| WEPMA010 | First Test Results of the BERLinPro 2-cell Booster Cavities | 2765 |
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| The BERLinPro Energy Recovery Linac (ERL) is currently being built at Helmholtz-Zentrum Berlin in order to study the physics of operating a high current, a 100 mA, 50 MeV ERL utilizing all SRF cavity technology. This machine will utilize three unique SRF cryomodules for the photoinjector, booster and linac cryomodules respectively. The focus of this paper will be on the cavities contained within the booster cryomodule. Here there will be three 2-cell SRF cavities, based on the original design by Cornell University, but optimized to meet the needs of the project. All of the cavity fabrication, processing and testing was carried out at Jefferson Laboratory where 4 cavities were produced and the 3 cavities with the best RF performance were fitted with helium vessels for installation in the cryomodule. This paper will report on the test results of the cavities as measured in the vertical testing dewar at JLab after fabrication and again after outfitting with the helium vessels. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPMA010 | |
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| WEPMA011 | First Horizontal Test Results of the HZB SRF Photoinjector for BERLinPro | 2768 |
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| The BERLinPro project, a small superconducting RF (SRF) c.w. energy recovery linac (ERL) is being built at Helmholtz-Zentrum Berlin in order to develop the technology required for operation of a high current, 100 mA, 50 MeV ERL. The electron source for the accelerator is a 1.4 cell SRF photoinjector fitted with a multi-alkali photocathode. As part of the HZB photoinjector development program three different SRF photoinjectors will be fabricated and tested. The photoinjector described herein is the second cavity that has been fabricated, and the first photoinjector designed for use with a multi-alkali photocathode. The photoinjector has been built and tested at JLab and subsequently shipped to HZB for testing in the horizontal test cryostat HoBiCaT prior to installation in the photoinjector cryomodule. This cryomodule will be used to measure the photocathode operation in a dedicated experiment called GunLab, the precursor to installation in the BERLinPro hall. This paper will report on the final results of the cavity installed in the helium vessel in the vertical testing dewar at Jefferson Lab as well as the first horizontal test in HoBiCaT | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPMA011 | |
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| WEPMA012 | High-Q Cavity Operation: Study on the Thermoelectrically Induced Contribution to RF Surface Resistance | 2771 |
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| We present a study concerning the operation of a superconducting RF cavity (non-doped niobium) in horizontal testing with the focus on understanding the thermoelectrically induced contribution to the surface resistance. Starting in 2009, we suggested a means of reducing the residual resistance by warming up a cavity after initial cooldown to about 20K and cooling it down again. In subsequent studies we used this technique to manipulate the residual resistance by more than a factor of 2. We postulated that thermocurrents during cooldown generate additional trapped magnetic flux that impacts the cavity quality factor. Since several questions remained open, we present here a more extensive study including measurement of two additional passband modes of the 9-cell cavity that confirms the effect. We also discuss simulations that substantiate the claim. While the layout of the cavity LHe tank system is cylindrically symmetric, we show that the temperature dependence of the material parameters result in a non-symmetric current distribution. Hence a significant amount of magnetic flux can be generated at the RF surface resulting in an increased surface resistance. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPMA012 | |
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| WEPMA013 | Hom Damping Optimization Design Studies for BESSY VSR Cavities | 2774 |
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| The BESSY VSR project is a future upgrade of the 3rd generation BESSY II light source. By using the same "standard" user optics, simultaneously long (ca. 15ps) and short (ca. 1.5ps) bunches will be stored. Thus, superconducting higher harmonic cavities of the fundamental 500 MHz at two frequencies need to be installed in the BESSY II storage ring. This work describes the optimizations studies for the Waveguide-based HOM dampers and the adjustable fundamental power coupler for the 1.5 GHz first SRF cavity prototype. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPMA013 | |
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| WEPMA014 | Development of New Microcontroller Based Power Supply Control Units at ELSA | 2777 |
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| At the electron stretcher facility ELSA electrons are accelerated with a high ramping speed of 6 GeV/s. This leads to strong requirements on the main magnets power supplies. In particular, any synchronization errors directly result in beam tune shifts and, at worst, beam loss. The existing thirty years old control units are now being replaced by new in-house developed versatile microcontroller based ones. These allow the application of arbitrary ramp patterns and actual value acquisition in realtime. With an ethernet interface the ramp patterns can be uploaded directly to the power supplies. The flexible design also allows usage of the module to control other power supplies, e.g. those of the orbit correction magnets. This presentation will give details on the developed hardware design and the performance of the modules compared to the existing ones. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPMA014 | |
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| WEPMA015 | Water-cooled Thin Walled Beam Pipes of the Fast Ramping Storage Ring ELSA | 2780 |
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| At the Electron Stretcher Facility ELSA of Bonn University thin walled beam pipes are in use to reduce eddy current loss to a minimum. The operation of the accelerator places high demands on the beam pipes like static stress because of the inner vacuum and additional one-sided thermal stress caused by synchrotron radiation. A first generation of thin walled beam pipes had been developed and manufactured during the construction of the stretcher ring in 1985. These pipes were successfully in operating stage the following ten years. The beam pipes had a wall thickness of 0.3mm, a length of 3m, and a bending radius of ca. 10.5m. Special pipes with a sideway branch for synchrotron radiation experiments have been manufactured in the same assembly dimension. In the course of an intensity upgrade, a second generation of beam pipes has been developed in 1995. To reduce the thermal stress caused by the synchrotron radiation an internal water cooling was mounted. In this contribution the design and manufacturing principles of the thin walled beam pipes with water cooling are presented. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPMA015 | |
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| WEPMA016 | A New RF station for the ELSA Stretcher Ring | 2783 |
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| At the Electron Stretcher Facility ELSA of Bonn University, an increase of the maximum stored beam current from 20 mA to 200 mA is planned. The storage ring operates applying a fast energy ramp of 6 GeV/s from 1.2 GeV to 3.2 GeV and afterwards a slow extraction over a few seconds to the hadron physics experiments. The beam current is mainly limited due to missing RF power at highest energies in order to compensate for synchrotron radiation losses. The current stretcher ring's RF station is based on a single 200 kW klystron driving two 5-cell PETRA type cavities. To achieve the desired beam current at maximum energy two additional 7-cell PETRA type cavities, drivin by a second klystron, will be installed. With this upgrade, sufficient beam lifetime for slow beam extraction will be provided and thus ensure an adequate duty cycle of the external beam current. The general setup of the new RF station as well as the changes in operation when switching from one to two stations will be presented. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPMA016 | |
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| WEPMA017 | Alvarez DTL Cavity Design for the UNLAC Upgrade | 2786 |
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| The 108.4 MHz drift tube linac (DTL) accelerator for GSI’s UNLAC upgrade project is in its initial design stage using CST-MWS code. Optimization criteria for cavity design are effective shunt impedance (ZTT), transit-time factor, and electrical breakdown limit. In geometrical op-timization we have aimed at increase of the energy gain in each RF gap of the DTL cells by maximizing ZTT per peak surface field with special designed tube profile. Mul-ti-pacting probability is evaluated for one gap of typical single cell. For the beta profile design, a code based on VBA macros of CST is developed to perform cell by cell design with pre-optimized 3D tube structures. With this code several beta profile designs are presented and com-pared for the balance of power consumption, ZTT, tank length, and breakdown possibility of the complete cavity. The stability of the field has been taken into account and for this the crossed stem arrangement is assessed. This paper gives a short introduction of the method, presents some important results. Possible countermeas-ures are discussed. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPMA017 | |
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| WEPMA018 | Status of the Ring RF Systems for FAIR | 2789 |
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| For the FAIR (Facility for Antiproton and Ion Research) synchrotron SIS100 and the storage ring CR (Collector Ring), different RF cavity systems are currently being realized. In addition to the standard RF bucket generation and acceleration, these ring RF systems also allow more complex beam manipulations such as barrier bucket operation or bunch rotation in phase space. Depending on their purpose, the cavities are either loaded with ferrite material or with MA (Magnetic Alloy) ring cores. Independent of the type of cavity, a complete cavity system consists of the cavity itself, a tetrode-based power amplifier, a solid-state pre-amplifier, a supply unit including PLC (Programmable Logic Control), and an RF control system (so-called LLRF, low level RF system). In this contribution, the different systems are described, and their current status is presented. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPMA018 | |
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| WEPMA019 | Status of the Super-FRS Magnet Devlopment for Fair | 2792 |
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| The Super FRS is a two-stage in flight separator to be built next to the site of GSI, Darmstadt, Germany as part of FAIR (Facility for Anti-proton and Ion Research). Its purpose is to create and separate rare isotope beams and to enable the mass measurement also for very short lived nuclei. Due to its three branches a wide variety of experiments can be carried out in frame of the NUSTAR collaboration. Due to the large acceptance needed, the magnets of the Super-FRS have to have a large aperture and therefore only a superconducting solution is feasible. A superferric design with superconducting coils was chosen in which the magnetic field is shaped by an iron yoke. We will present the actual design status of the dipole- and multipole magnets as well as the status of the development of the dedicated test facility at CERN. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPMA019 | |
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| WEPMA020 | SIS100 Dipole Field Harmonics and Dynamic Aperture Calculations | 2795 |
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| During the acceptance test of the First of Series (FoS) SIS100 super-ferric dipole, detailed field measurements have been done. The harmonic coefficients have been extracted from these and dynamic aperture simulations have been done which are presented here. Furthermore, geometric precision measurement tools for the magnet have been developed to track down the field errors to geometric errors. Finally, mitigation actions have been taken to reduce these errors during manufacturing to ensure the design beam survival rate in SIS100. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPMA020 | |
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| WEPMA021 | Efficient Pulsed Quadrupole | 2799 |
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Funding: Work supported by EuCARD-2-WP03-EnEfficient. EuCARD-2 is co-funded by the partners and the European Commission under Capacities 7th Framework Programme, Grant Agreement 312453 In order to raise the focusing gradient in case of bunched beam lines, an alternative, iron free, pulsed quadrupole was designed. The transfer channels between synchrotrons as well as the final focusing for the production of secondary beams are possible applications. The quadrupole is running in a pulsed mode, which means an immense saving of energy by avoiding standby operation. Still the high gradients demand high currents. Hence a circuit had to be developed which is able to recover a significant amount of the pulsing energy for following shots. The basic design of the electrical circuit of the pulsed quadrupole is introduced. Furthermore more energy efficient circuits are presented and the limits of adaptability are considered. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPMA021 | |
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| WEPMA022 | Progress of the Klystron and Cavity Test Stand for the FAIR Proton Linac | 2802 |
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| In collaboration between the FAIR project, GSI, and CNRS, the IPNO lab provided the high power RF components for a cavity and klystron test stand. For initial operation of the 3 MW Thales TH2181 klystron at 325.224 MHz we received a high voltage modulator from CERN Linac 4 as a loan. Here we report, how we integrated the combination of klystron, high voltage modulator, and auxiliaries to accumulate operating experience. RF operation of the klystron started on a water cooled load, soon the circulator will be included and then the prototype CH cavity in the radiation shielded area will be powered. The 45 kW amplifiers for the 3 buncher structures of the FAIR proton Linac were checked at the test stand, and the results are presented here. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPMA022 | |
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| WEPMA023 | Advanced Multipoles and Appropriated Measurement Tools for Field Characterization of SIS100 Magnets | 2805 |
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| The heavy ion synchrotron SIS100 utilises fast ramped superconducting magnets. Describing and measuring these magnets requires advanced multipoles next to well adapted measurement techniques. We cover briefly the required theory adapted to the measurements, show which designs were available and which decisions had to be taken for measuring curved superconducting magnets. The series of SIS100 dipole magnets is going to be produced. These magnets will be measured at GSI. We present the foreseen field measurement procedure, outline the currently ongoing tests and give our calibration strategy. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPMA023 | |
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| WEPMA024 | System Design for a Deterministic Bunch-to-Bucket Transfer | 2809 |
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Funding: Supported by GSI and the Technical University Darmstadt in the frame of the cooperation for FAIR. A deterministic bunch to bucket transfer system is currently under development in the frame of the FAIR project at GSI. To achieve our accuracy and stability requirements, a set of hardware modules will be implemented. These hardware modules are expected to provide values such as the relative phase advance between the RF systems of both, the source and the target synchrotron according to an external timing system. These values are exchanged via optical fibers between different supply rooms, and the considered RF signals are re-synthesized locally. These re-synthesized signals are synchronized to enable a precise phase advance control between the synchrotrons’ RF systems. The first step of the development consists in modeling the actual DDS and DSP-based LLRF environment of the SIS18 under Ptolemy-II. Measurements on real devices will be performed concurrently to the simulation. We expect to use this simulation to refine our timing expectations regarding the synchronization process and the inter-module communication protocols and design the synchronization function, which will be implemented on the hardware modules. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPMA024 | |
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| WEPMA026 | Higher Order Mode Propagation and Damping Studies on Axisymmetric Superconducting Multicell RF-Resonators | 2812 |
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Funding: Work supported by the BMBF under contract no. 05K13PEB Higher order mode (HOM) propagation and damping is a major concern in feasibility studies regarding the upcoming upgrade of BESSY II, named BESSY-VSR*, which involves the utilization of superconducting multicell RF-resonators in a storage ring while maintaining a reasonably high beam current typical for third generation synchrotron radiation facilities. In addition to the computation of the typical figures of merit, we focus on studies of the mode propagation in axisymmetric structures. Due to the focus on axisymmetric studies we are able to use 2D codes to investigate in eigenmodes with substantial higher frequencies than usually considered with full 3D codes in parametric studies. In this work we present preliminary studies involving mode propagation in superconducting elliptical multicell cavities. * G. Wüstefeld et al., Proc. of IPAC'11, San Sebastián, THPC014 |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPMA026 | |
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| WEPMA027 | First Characterization of a Superconducting Undulator Mockup with the CASPER II Magnetic Measurement System | 2815 |
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| Superconducting insertion devices (IDs) can reach, for the same gap and period length a higher field strength compared to permanent magnet IDs. Their performance depends strongly on the magnetic field quality. While the magnetic measurements technology of permanent magnet based IDs made significant progress during the last years, for superconducting IDs similar major developments are necessary. As a part of our R&D program for superconducting insertion devices at the ANKA synchrotron light source a measurement setup for conduction cooled superconducting coils with a maximum length of 2 m was built and commissioned. In the CASPER II (Characterization Setup for Phase Error Reduction) facility the magnet coils can be trained and tested for maximum current and field quality, including the local field distribution as well as the first and second field integrals. In this paper we shortly describe the CASPER II setup and focus on the capability of this measurement device by presenting the results of a superconducting undulator mockup with a period length of 20 mm. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPMA027 | |
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| WEPMA029 | Design of a Normal Conducting Cavity for Arrival Time Stabilization at FLASH | 2818 |
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| It has been shown, that beam-based feedback loops stabilize the bunch arrival time in the femtoseconds range. However, further minimizing the bunch arrival time jitter requires a faster actuator that is a normal conducting cavity with higher bandwidth compared to narrow-band superconducting cavities. We present the design of a 4-cell normal conducting cavity that is going to be used in a fast beam-based feedback at free-electron laser FLASH at Hamburg. The input power will be injected to the cavity via a loop coupler from the side of the first cell. The operating frequency of the designed cavity is about 3 GHz with an adjustable bandwidth. The long range longitudinal wakefield calculation results are reported to investigate the cavity performance for multi-beam operation up to 3 MHz bunch repetition rate. The results declare that the influence of the long range wakefield on the arrival time jitter is less than 1 fs. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPMA029 | |
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| WEPMA030 | Design and Characterization of Permanent Magnetic Solenoids for REGAE | 2822 |
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| REGAE is a small electron linear accelerator at DESY. In order to focus short and low charged electron bunches down to a few micrometre permanent magnetic solenoids were designed, assembled and field measurements were done. Due to a shortage of space close to the operation area an in-vacuum solution has been chosen. Furthermore a tworing design made of wedges has been preferred in terms of beam dynamic issues. To keep the field quality of a piecewise built magnet still high a sorting algorithm for the wedge arrangement has been developed and used for the construction of the magnets. The magnetic field of these solenoids has been measured with high precision and has been compared to the simulated magnetic field. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPMA030 | |
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| WEPMA031 | Timing Jitter Studies for sub-fs Electron Bunch Generation at SINBAD | 2826 |
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| Generation of ultra-short electron bunches with a few femtoseconds arrival-time jitter is the major challenge in plasma acceleration with external injection. Meanwhile, peak current stability is also one of the crucial factors for user experiments when the electron bunch is used for free-electron laser (FEL) generation. ARES (Accelerator Research Experiment at SINBAD) will consist of a compact S-band normal-conducting photo-injector providing ultra-short electron bunches of 100 MeV. We present bunch arrival-time jitter studies for two different compression schemes, velocity bunching and magnetic compression with a slit, at ARES with start-to-end simulations. Contributions from various jitter sources are quantified. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPMA031 | |
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| WEPMA033 | Utilizing Gas Filled Cavities for the Generation of an Intense Muon Source | 2829 |
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Funding: This manuscript has been authored by employees of Brookhaven Science Associates, LLC under Contract No. DE-SC0012704 with the U.S. Department of Energy. A key requirement for designing intense muon sources is operating rf cavities in multi-tesla magnetic fields. Recently, a proof-of-principle experiment demonstrated that an rf cavity filed with high pressure hydrogen gas could meet this goal. In this study, rigorous simulation is used to design and evaluate the performance of an intense muon source with gas filled cavities. We present a new lattice design and compare our results with conventional schemes. We detail the influence of gas pressure on the muon production rate. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPMA033 | |
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| WEPMA034 | Bakeout Concept for the HESR at FAIR | 2832 |
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| Forschungszentrum Jülich has taken the leadership of a consortium being responsible for the design of the High-Energy Storage Ring (HESR) going to be part of the FAIR project at GSI. The HESR is designed for antiprotons but can be used for heavy ion experiments as well. Therefore the vacuum is expected to be 10-11 mbar or better. To achieve this also in the curved sections where 44 bent dipole magnets with a length of around 4.5 m will be installed, NEG coated dipole chambers will be used to reach the needed pumping speed and capacity. For activation of the NEG-material a bakeout system must be installed. The bakeout concept including the layout of the control system and the systematization of the heater packages for all components of the vacuum system are presented. Also the special design of the heater jackets inside the dipole will be shown where the geometrical parameters are very critical and space is very limited. The results of the simulation of temperature distribution in the dipole iron are compared to temperature measurements carried out at a testbench with different layouts of the heater jackets. The final design of the dipole heater jackets will be illustrated. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPMA034 | |
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| WEPMA035 | Low- and High-Beta SRF Elliptical Cavity Stiffening | 2835 |
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| Elliptical SRF cavities are the main accelerating structures in many accelerators worldwide. Different types of external loads on the resonator walls predetermine the main working conditions of the SC cavities. The most important of them are very high electromagnetic fields that result in strong Lorentz forces and the pressure on cavity walls from the helium tank that also deforms the cavity shape. Also mechanical eigen resonances of cavities are the main source of the microphonics. To withstand any kind of external loads on the resonator walls different schemes of the cavity stiffening were applied. In the paper we report the basic investigations of the cavity stiffening using FNAL 650 MHz β=0.92 and 0.61 as an example. The single-cell investigation results were used as the reference to develop the ultimate scheme of the helium vessel structure to ensure the best resonator stability. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPMA035 | |
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| WEPMA036 | Double-Cell Notch Filter for SRF Gun Investigations | 2838 |
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| Some projects of SRF guns apply the design where the cathode can be easily and quickly removed. One of the disadvantages of this design is the RF power leakage from the accelerating gun cavity cells to the cathode housing that results in the excessive cathode heating. To minimize the RF power leak different kinds of choke filters are used to protect the cathode structure. These choke filters represent resonant circuits with a zero input impedance and installed at the entrance of the cathode structure that shunt the cathode housing. Still, since the choke filter frequency shift under working conditions is bigger than its bandwidth a filter tuning during assembly only in the warm stage seems insufficient and requires also fine-tuning during operation. To eliminate the problems of the choke filter fine-tuning and hence ensure its stability during operation, a combination of the resonance choke elements can be implemented. In the paper we demonstrate advantages of the double-cell notch filter using BERLinPro SRF gun cavity as an example with its simple design modifications. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPMA036 | |
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| WEPMA037 | Manufacturing and First Test Results of Euclid SRF Conical Half-wave Resonator | 2841 |
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Funding: This Work is supported by the DOE SBIR Program, contract # DE-SC0006302. Euclid TechLabs has developed a superconducting conical half-wave resonator (162.5 MHz β=v/c=0.11) for the high-intensity proton accelerator complex proposed at Fermi National Accelerator Laboratory. The main objective of this project is to provide a resonator design with high mechanical stability based on an idea of the balancing cavity frequency shifts caused by external loads. A unique cavity side-tuning option has been successfully implemented. Niowave, Inc. proposed a complete cavity production procedure including preparation of technical drawings, processing steps and resonator high-gradient tests. During manufacturing a series of cavity and helium vessel modifications to simplify their manufacturing were proposed. Following standard buffered chemical polish surface treatment and high-pressure rinse, a vertical test was carried out at Niowave’s facilities. Here we present the status of the project and the first high-gradient results. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPMA037 | |
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| WEPMA038 | Compact In-vacuum Quadrupoles for a Beam Transport System at a Laser Wakefield Accelerator | 2845 |
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Funding: This work is partially funded by the German Federal Ministry for Education and Research under contract no. 05K10VK2 and 05K10SJ2. For the transport and matching of electrons generated by a Laser Wakefield Accelerator (LWFA) a beam transport system with strong focusing magnets and a compact design is required. For the realization of such a beam transport system at the LWFA in Jena, Germany, two small series of inexpensive, modular quadrupoles were designed and built. The quadrupoles are iron-dominated electromagnets in order to keep the transport system adaptable to different energies and target parameters. To achieve the required field strength it was necessary to choose a small magnetic aperture. Therefore the magnets were designed for in-vacuum use with water-cooled coils. In this contribution the design, the realization and first field measurements of these quadrupoles are presented. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPMA038 | |
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| WEPMA040 | Magnet Studies for the Accelerator FLUTE at KIT | 2849 |
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| At KIT we are currently constructing the compact linear accelerator FLUTE (Ferninfrarot Linac Und Test Experiment). This 41 MeV machine is aimed at accelerator physics and synchrotron radiation research, using ultra-short electron bunches. The electrons are generated at a photo-cathode using picosecond long UV laser pulses. A magnetic chicane is used to compress the bunches longitudinally to a few femtoseconds. This contribution describes both the magnet design, in particular the optimization of the chicane dipoles based on finite element method (FEM) simulations, as well as the implementation of a magnet measurement system. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPMA040 | |
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| WEPMA041 | 1.3 GHz SRF Cryomodules for the Mainz Energy-recovering Superconducting Accelerator MESA | 2853 |
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Funding: Work supported by the German Federal Ministery of Education and Research (BMBF) and German Research Foundation (DFG) under the Cluster of Excellence "PRISMA" The Mainz Energy-recovering Superconducting Accelerator MESA requires superconducting RF systems that provide sufficient energy of 50 MeV per turn to an electron beam. The ordering process of two Rossendorf-type cryomodules, containing two 9-cell 1.3 GHz XFEL-like cavities each, is in progress. Besides an overview of the adaptations required for the multipass and high current beam operation of the cryomodules, details about challenges regarding the installation of the cryomodules on the premises of the Institut für Kernphysik at Universität Mainz are given. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPMA041 | |
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| WEPMA042 | Experience and Developments on the S-band RF Power System of the FERMI Linac | 2856 |
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| The S-band linac of FERMI, the seeded Free Electron Laser (FEL) located at the Elettra laboratory in Trieste, operates on a 24/7 basis accumulating more than 6000 hours of operation per year. The performance and operability requirements of a users facility pose stringent specifications on reliability and availability on all the systems of the machine and in particular on the RF power plants. This paper provides a review and discusses the operational experience with the S-band power plants, klystrons and modulators, operating at S-band in FERMI. Based on the satisfactorily results and following return of experience, upgrades of the existing power plants are being implemented in the continuous effort of extending the operability and availability of the systems. A description of these activities and an overview of the other developments under consideration on the RF power plants are also provided. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPMA042 | |
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| WEPMA043 | Five Years of Operations for the Magnet Power Supplies of FERMI | 2859 |
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| FERMI, the FEL light source in Trieste, Italy, started its regular operation with external users in 2012. The construction of the facility began in 2008 and the commissioning of the complete system – LINAC, Undulators’ chains (FEL-1 and FEL-2), photon front-end – started in 2010. On December 13, 2010 the first lasing occurred. From the Photo-injector to the electron Main Beam Dump (MBD), there are more than 400 magnets and coils, including those mounted on the accelerating sections of the LINAC and on the Undulators. With few exceptions, each magnet power supply energizes a single magnet/coil: there are about 400 magnet power supplies spanning from few tens of watt up to 42 kW. The power supplies types range from custom-made ones, to COTS (Commercial Off The Shelf), to in-house design (these accounting to 88% of the total). Almost all magnet power supplies are in use since mid-2010. During 5 years of operations, the reliability of the magnet power supplies proved to be extremely high: the downtime of FERMI operations due to magnet power supplies is very low. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPMA043 | |
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| WEPMA044 | 25 Hz, Sub-mJ Ytterbium Laser Source of RF Gun for SuperKEKB Linac | 2862 |
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| For injector linac of SuperKEKB project, the 5 nC electron beams with double-bunch is expected to be generated in the photocathode RF gun. For the repetition rate of electrum beam, the optional of 2 Hz, 5 Hz, 25 Hz and 50 Hz are requested. Although, more than 5 nC electron with single-bunch has been generated in the 2 Hz and 5 Hz, when the repetition rate increases to 25 Hz, the condition of the laser amplifier system such as the thermal lens effect is changed seriously. To correspond to 25 Hz repetition rate, the ytterbium-doped laser system was reformed. An AuSu (80:20) heat-dissipating solder is employed to reduce the thermal lens effect. Because of the damage threshold limitation of the thin-disk crystal and optical mirrors, Some improvement were performed to increase the quality of the pulses rather than the amplify power, which cause the SHG conversion efficiency is up to 60% and 30% with 2ω and 4ω respectively. More than 3 nC electron beam is obtained with 25 Hz. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPMA044 | |
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| WEPMA045 | Energy Deposition and DPA in the Superconducting Links for the HiLumi LHC project at the LHC Interaction Points | 2865 |
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Funding: The work is part of HiLumi LHC Design Study, partly funded by the European Commission, GA 284404, and included in the High Luminosity LHC project. In the framework of the upgrade of the LHC machine, the powering of the LHC magnets foresees the removal of the power converters and distribution feedboxes from the tunnel and its location at the surface[1]. The Magnesium Diboride (MgB2) connecting lines in the tunnel will be exposed to the debris from 7+7 TeV p-p interaction. The Superconducting (SC) Links will arrive from the surface to the tunnel near the separation dipole, at about 80 m from the Interaction Point at IP1 and IP5. The Connection Box (where the cables of the SC Links are connected to the NbTi bus bar) will be close to the beam pipe. The debris and its effect on the MgB2 SC links in the connection box (energy deposition and displacement per atom) are presented. The effect of thermal neutrons on the Boron consumption and the contribution of the lithium nucleus and the alpha particle on the DPA are evaluated. The results are normalized to an integrated luminosity of 3000 fb-1, value that represents the LHC High Luminosity lifetime. The dose delivered to the SC Links is found to be below the damage limit. Further studies are necessary to correlate the induced displacement per atom to the superconducting properties. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPMA045 | |
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| WEPMA046 | Studies on Innovative Production methods of HOM Coupler for SRF 9-cell Cavity | 2869 |
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| Pure Nb as the material of SRF cavity bears hard workability in general. This is why both the inner and outer conductors of HOM coupler for 9-cell cavity have been conventionally produced by full machining, backward extrusion accompanied with annealing and so on. However, in the mass production of 9-cell cavities in ILC, further cost reduction is required. We produced both the inner and outer conductors of HOM coupler for 9-cell cavity in the advanced press forming methods aiming at cost reduction. Press forming of a pure Nb sheet for the outer conductor of HOM coupler was performed with fewer processes free from intermediate annealing and primary machining. For the inner conductor of HOM coupler, water jet cutting and press cold-forging of a plate was performed. The above advanced press forming methods showed favored results, leading to a possibility of simple mass-production of components and cost reduction. The vertical test on a 9-cell cavity with the press formed HOM couplers achieved 36 MV/m that is beyond ILC qualification. The R＆D works are ongoing for further improvement. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPMA046 | |
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| WEPMA047 | MHI's Production Activities of Accelerator Components | 2873 |
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| Mitsubishi Heavy Industries (MHI) is manufacturing various types of accelerator components. Recent production activities, mainly in a field of a normal conducting RF, will be reported in this presentation. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPMA047 | |
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| WEPMA048 | Development for Mass Production of Superconducting Cavity by MHI | 2876 |
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| Mitsubishi Heavy Industries (MHI) have developed manufacturing process of superconducting cavitis for a long time. In this presentation, recent progress will be reported. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPMA048 | |
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| WEPMA049 | Development of the Ceramic Chamber Integrated Pulsed Magnet Fitting for a Narrow Gap | 2879 |
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| We are pushing forward the development of a pulsed magnet that has a combined structure of magnet coils with a ceramic vacuum chamber, aiming to realize a small gap. The structure we are developing is that single turn air-coils are implanted along the longitudinal axis in the cylindrical ceramic chamber wall with thickness of 5mm. The ceramic wall works for separating the vacuum from the atmosphere, as well as holding the coil structures mechanically and the electrical insulation of coils. By this structure, magnet pole edges can be set close to the inside diameter of the chamber. The small gap increases magnetic field strength, which is for shorter length, and, as a result, the small magnet size reduces the inductance, which is for shorter pulse. We achieved the continuous operation over 200 days, without any failure, of current-excitation with 20 kV, 7.7 kA pulse with 4-μsec width and repetition of 1 Hz, using the dipole type prototype with a bore radius of 30 mm and magnetic length of 0.3m in 2013, while maintaining the vacuum pressure less than 10-6 Pa. In this conference, we will discuss about the availability and practical utility with the magnetic field output performance. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPMA049 | |
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| WEPMA050 | Permanent Dipole Magnet R&D for SPring-8-II | 2883 |
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Permanent magnets are promising for future light source machines with its compactness, small power consumption. We have proposed a variable-field permanent dipole magnet and demonstrated its performance*. Following the result, a prototype magnet with a longitudinal field gradient and a magnetic shunt circuit was designed and fabricated. The longitudinal field gradient enables a lower beam emittance and the magnetic shunt circuit improves a temperature stability of the magnetic field strength. Simulation studies and measurement results are presented in this report. The interference of magnetic fields between neighboring magnets was also investigated.
* T. Watanabe et al., Proc. of IPAC 2014. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPMA050 | |
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| WEPMA051 | Superconducting Solenoid Package Prototyping for FRIB SRF Linac | 2886 |
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Funding: This material is based upon work supported by the U.S. Department of Energy Office of Science under Coopertive Agreement DESC000661. FRIB is an under constructing machine in USA for nuclear physics, which has intensity front SRF linacs to accelerate ion beam from proton to uranium up to 200 MeV/u. FRIB has large users community, so the machine has to be operated very reliably and stably. Superconducting solenoid and steering dipoles as a package is mounted in the cryomodule nearby SRF cavities to focus beam strongly and space effectively. This produces an issue interacting between the fringe field from the solenoid and the SRF cavity, which makes potential performance degradation on SRF cavity. NbTi superconducting wire is utilized for the solenoid package. The high field design like 9T is very critical operation due to the SC characteristics of the wire. The solenoid package has to be designed very carefully. In this paper will report the prototyping of 25 cm 8T solenoid package for FRIB cryomodule, which includes design, fabrication, and cold test. * This work has been done under the collaboration between KEK and MSU. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPMA051 | |
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| WEPMA052 | Low Level RF Systems for J-PARC Linac 50-mA Operation | 2889 |
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| In the summer of 2014, lots of improvements were carried out in the J-PARC proton linac, including the ion source, the Radio Frequency Quadrupole linac (RFQ), and the medium-energy beam-transport line from the RFQ to the Drift Tube Linac (DTL) called as MEBT1. The output beam current of the ion source was upgraded from 20 to 50 mA. The previous RFQ with two RF power input ports was replaced by a newly developed RFQ with one input port. The RF power of the solid state amplifier for the rf cavities used in the MEBT1 section were upgraded; from 10 to 30 kW for both of the Buncher-1 and Buncher-2, and from 30 to 120 kW for the Chopper cavity. The old scraper used as dump of chopped beam after the Chopper cavity was also replaced by a new dump system using two scrapers; A new function of separating the chopped beam automatically to the two scrapers was developed by modifying the FPAG control program in the low level control systems. After those improvements, in the September 2014 the J-PARC linac was successfully upgraded for 50-mA beam operation. The details of the improvments, especially for the low level RF systems, will be reported in this paper. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPMA052 | |
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| WEPMA053 | Multipactor Simulations in 325 MHz Superconducting Spoke Cavity for an Electron Accelerator | 2892 |
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Funding: The work is supported by Photon and Quantum Basic Research Coordinated Development Program from the Ministry of Education, Culture, Sports, Science and Technology, Japan. In order to realize a compact industrial-use X-ray source with the laser-Compton scattering, a 325MHz superconducting spoke cavity for an electron accelerator operated at 4K is under development. After design-optimizations of the first cavity, we started fabrication process. In this paper, multipactor analyses carried out as parts of the design-optimization efforts are briefly summarized. Relations between cavity geometries and averaged secondary electron emission yield are discussed. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPMA053 | |
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| WEPMA054 | A Disturbance-Observer-based Controller for LLRF Systems | 2895 |
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| Digital low-level radio frequency (LLRFs) systems have been developed and evaluated in the compact energy recovery linac (cERL) at KEK. The required RF stabilities are 0.1% rms in amplitude and 0.1° rms in phase. These requirements are satisfied by applying digital LLRF systems. To further enhance the control system and make it robust to disturbances such as large power supply (PS) ripples and high-intensity beams, we have designed and developed a disturbance observer (DOB)-based control method. This method utilizes the RF system model, which can be acquired using modern system identification methods. Experiments show that the proposed DOB-based controller is more effective in the presence of high disturbances compared with the conventional proportional and integral (PI) controller. In this paper, we present the preliminary results based on the experiments with DOB-based controller. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPMA054 | |
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| WEPMA055 | The Magnet and Power Supply System for the Compact-ERL | 2899 |
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| The recirculation loop of the cERL (compact Energy Recovery LINAC) was constructed in 2013. In this paper, we show the magnet and the power supply system for the recirculation loop of the cERL. The recirculation loop consists of the eight main bending magnets, sixty quadrupole magnets and ten small bending magnets for the three chicanes of the injection, extraction and circumference adjuster. The four power supplies are used for the chicane bending magnets, sixty for the quadrupoles, forty-eight for the horizontal correctors, and thirty-three for the vertical correctors. The EPICS (Experimental Physics and Industrial Control System) was used for the control of the power supplies. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPMA055 | |
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| WEPMA056 | Development of Superconducting Spoke Cavities for Laser Compton Scattered X-ray Sources | 2902 |
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Funding: This study is supported by Photon and Quantum Basic Research Coordinated Development Program of MEXT, Japan. A 5-year research program on the development of superconducting spoke cavities for electron accelerators has been funded by MEXT, Japan since 2013. The purpose of our program is establishing design and fabrication processes of superconducting spoke cavity optimized for compact X-ray sources based on laser Compton scattering. The spoke cavity is expected to realize a compact industrial-use X-ray source with a reasonable cost and easy operation. We have chosen a cavity frequency at 325 MHz due to possible operation at 4 K and carried out cavity shape optimization in terms of electromagnetic and mechanical properties. Production of press-forming dies is also in progress. In this paper, we present overview and up-to-date status of the research program. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPMA056 | |
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| WEPMA057 | Development of HTS magnets | 2905 |
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| We have been developing magnets utilizing high-temperature superconducting (HTS) wires for this decade. We built three model magnets, a mirror coil for an ECR ion source, a set of coils for a scanning magnet and a super-ferric dipole magnet to generate magnetic field of 3 T. They were excited with AC/pulse currents as well as DC currents. Recently we fabricated a cylindrical magnet for a practical use which polarizes ultracold neutrons (UCN). It consists of 10 double pancakes and the field strength at the center is higher than 3.5 T which is required to fully polarize 210 neV neutrons. It was successfully cooled and excited. The magnet was used to polarized UCN generated by the RCNP-KEK superthermal UCN source, One dipole magnet has been manufactured which is used as a switching magnet after the RCNP ring cyclotron and is excited by pulse currents. It becomes possible to deliver beams to two experimental halls by time sharing. Their designs and performances are presented in the talk. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPMA057 | |
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| WEPMA058 | New Injection Bump Power Supply of the J-PARC RCS* | 2908 |
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| The new horizontal shift bump (SB) power supply for beam injection system of the J-PARC (Japan Proton Accelerator Research Complex) 3-GeV RCS (Rapid-Cycling Synchrotron) has been developed and manufactured. The injection energy was increased from 181 MeV to 400 MeV, and the power capacity of the new power supply was doubled. The power supply newly adopted a capacitor commutation method to form the trapezoid waveform pattern (bump waveform) by the IGBT (Insulated Gate Bipolar Transistor) switch. This paper reports characteristic, the problems and the user operation status about the new shift bump power supply. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPMA058 | |
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| WEPMA059 | Degassing of Kicker Magnet by In-situ Bake-out Method | 2911 |
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| New method of in-situ degassing of the kicker magnet in the beam line has been developed. The heater and heat shielding panels are installed in the vacuum chamber in this method. The heater was designed considering the maintainability. The graphite was selected as the heater and the high melting point metals were used as the reflectors just near the heater. The thermal analysis and the temperature measurement with the designed heater was performed. The ideal temperature distribution for the kicker degassing was obtained. The outgassing of the graphite during rising the temperature was measured. The result showed that the outgassing was extremely suppressed by the first heating. This means the outgassing of the graphite heater was negligible as long as it is used in the beam line without exposure to the air. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPMA059 | |
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| WEPMA060 | The Development of Cavity Frequency Tracking Type RF Control System for SRF-TEM | 2914 |
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| Superconducting accelerating cavities used in high-energy accelerators can generate high electric fields of several 10 MV/m by supplying radio frequency waves (RF) with frequencies matched with resonant frequencies of the cavities. Generally, frequencies of input RFs are fixed, and resonant frequencies of cavities that are fluctuated by Lorentz force detuning and Microphonics are corrected by feedbacks of cavity frequency tuners and input RF power. Now, we aim to develop the cavity frequency tracking type RF control system where the frequency of input RF is not fixed and consistently modulated to match the varying resonant frequency of the cavity. In KEK (Tsukuba, Japan), we are developing SRF-TEM that is a new type of transmission electron microscope using special-shaped superconducting cavity. By applying our new RF control system to the SRF-TEM, it is expected to obtain stable accelerating fields so that we can acquire good spatial resolution. In this presentation, we will explain the required stabilities of accelerating fields for SRF-TEM and the feasibility of SRF-TEM in the case of applying the cavity frequency tracking type RF control system. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPMA060 | |
| Export • | reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml) | |