Paper | Title | Other Keywords | Page |
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TUP006 | Improving the Superconducting Cavities and Operational Findings at the S-DALINAC | cavity, vacuum, superconducting-cavity, SRF | 395 |
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Funding: Work supported by the DFG through SFB 634 |
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TH101 | Superconducting RF R&D Toward High Gradient | cavity, SRF, HOM, superconducting-cavity | 725 |
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High-beta superconducting rf elliptical cavities are being developed in large numbers for several accelerator projects including the International Linear Collider (ILC). In recent years, the understanding of cavity performance limitations has improved significantly, leading to better than 40 MV/m in some cavities. However, further improvement is needed to reach reliably the 31.5 MV/m operating gradient proposed for the ILC Main Linac cavities. World-wide R&D on the cavity gradient frontier includes improved surface cleaning and smoothing treatments, development of alternative cavity shapes and materials, and novel cavity manufacturing techniques. Substantial progress has been made with diagnostic instrumentation to understand cavity performance limitations. Some highlights of the efforts in superconducting rf R&D toward achieving higher gradients in high-beta elliptical cavities are reviewed. |
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TH102 | SRF Developments for Ion Acceleration | cavity, linac, cryomodule, ion | 730 |
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The talk will provide an overview of the SRF development toward the acceleration of light and heavy ions including QWRs, HWRs, spoke and CH cavities. |
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TH202 | Heavy Ion Linac Booster at IUAC, New Delhi | linac, cavity, acceleration, ion | 749 |
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The first module of the booster superconducting linear accelerator, consisting of a total of three modules, each having 8 quarter wave coaxial line bulk Nb resonators, has been commissioned at IUAC. During initial operation of the first linac module, the energy gain was found to be much lower due to various problems which are now identified and solved. After acceleration through the linac module and subsequent re-bunching using a superconducting Rebuncher, a 158 MeV silicon beam having pulse width of 400 ps was delivered to conduct nuclear physics experiments. The other two linac cryostats and the required 16 resonators to be installed in those two cryostats are in the final stage of fabrication. Work has progressed on a high current injector that would act as an alternate source of heavy ions for the superconducting linac. The first element of the high current injector is a high Tc superconducting magnet ECR source (PKDELIS) which would be followed by a room temperature radio frequency quadrupole accelerator and drift tube linac cavities. Prototypes of the RFQ working at 48.5 MHz, and that of the DTL working at 97 MHz, have been fabricated and are undergoing tests. |
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THP001 | Nb-RRR Sheet Inspection by Means of Ultrasonic Microscopy | cavity, electron, diagnostics, superconducting-RF | 771 |
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Nb-RRR sheet material is one of the key components of super conducting linear particle accelerator projects (e.g. XFEL, ILC). The high quality requirements led to sophisticated quality systems in the manufacturing line. A major aspect is the development of non-destructive inspection methods for the detection of surface defects, delaminations, and inclusions. Up to now the standard inspection technologies for quality assurance of Nb-RRR sheet material are based on electromagnetic techniques, e.g. SQUID and eddy current. For these methods the detection limit is in the range of 0.1 mm. Ultrasonic microscopy (USM) in the frequency range of 1 GHz is a well established and economic technique for non-destructive surface inspection. For volume inspection of sheet material ultrasonic frequencies of 50 to 100 MHz are applied. For Nb-RRR sheets with typical thickness of 2.8 mm a detection limit of 0.1 mm is expected. First results of USM on Nb-RRR sheet material are presented. |
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THP008 | A Novel Frequency Tuning System Based on Movable Plunger for SPIRAL2 High-Beta Superconducting Quarter-Wave Resonator | cavity, cryomodule, simulation, insertion | 789 |
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SPIRAL2 aims at building a multi-purpose facility dedicated to nuclear physics studies, including the production of rich-neutrons isotopes. The multi-beam linear accelerator is composed of superconducting accelerating modules and warm focusing magnets. IPN Orsay is in charge of the high energy accelerating modules, each hosting two superconducting (β = 0.12) quarter-wave resonators operating at an accelerating field of 6.5 MV/m at 88 MHz. The static and dynamic frequency tuning is achieved by the insertion and motion of a niobium plunger into the magnetic field area. The efficiency of the tuning (1 kHz/mm) has been validated during the tests of the cryomodule. In this paper we discuss the impact of such a tuning system, based on experimental results on Spiral2 cavities, on the different aspects: maximum accelerating field, Qo slopes, quench, multipacting and microphonics. |
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THP012 | Nondestructive Testing of Niobium Sheets for SRF Cavities Using Eddy-current and SQUID Flaw Detection | cavity, controls, superconductivity, neutron | 800 |
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For more than 10 years DESY has been operating a high resolution eddy-current scanning installation with rotating table for nondestructive flaw detection on niobium sheets for SRF cavities. More than 2000 sheets have been examined up to now, several types of defects have been detected and identified using different supplementary methods such as EDX, X-ray fluorescence, neutron activation analysis etc. In order to scan Nb-sheets needed for XFEL-cavity production, new scanning devices have to be build. One option of the eddy-current installations could be an application of SQUID-sensors due to much higher sensitivity instead of conventional probes. A SQUID based scanner system was built and is in evaluation at DESY. A status report will be given. |
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THP014 | Recent Results of 1.3 GHz Nine-Cell Superconducting Cavities for the European XFEL | cavity, HOM, superconductivity, superconducting-cavity | 806 |
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In preparation for the series production of roughly 800 superconducting accelerating structures, several tests with an industrial-like production sequence have been tested for their accelerating gradient and quality factor. The main part of the surface preparation is being done with electropolishing. with ethanol rinse. For the two different final preparation steps namely electropolishing and etching the performance is compared. The results will be also put into the perspective of earlier cavity production cycles that were tested at DESY. |
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THP015 | Open 120C Bake in Argon Atmosphere: A Simplified Approach for Q-Drop Removal | cavity, vacuum, superconducting-cavity, controls | 809 |
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The removal of the Q-drop without field emission by a low temperature (app. 120C) bake procedure is essential in order to achieve the full performance in both electropolished (EP) and chemically etched (BCP) high gradient SCRF Nb accelerator cavities. A simplified procedure applying an open 120C bake out in an Argon atmosphere is presented. First results are compared to the well-established bake-out procedure under vacuum conditions. |
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THP017 | Use of Piezoelectric Actuator to Frequency Lock Superconducting Quarter Wave Resonator | controls, linac, high-voltage, resonance | 815 |
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The frequency control of the superconducting quarter wave resonator at IUAC is currently accomplished by mechanical and electronic tuners which are operated in the time scale of seconds and hundreds of milliseconds to a few tens of microseconds respectively. Due to presence of microphonics, input rf power in the range 200-300 W was required to control the resonator for a typical field of 3-5 MV/m achieved with 6 watts dissipation. Implementation of a novel idea to damp the mechanical vibration with the help of SS-balls has helped to reduce rf power below 100 W. Though resonators are working fine at this power level, we are investigating whether further reduction of rf power is possible using a piezo actuator to control the drift of frequency. The piezo tuner working in hundreds of milli seconds range with the dynamic phase control scheme will share a substantial load from the electronic tuner. As a result, the resonator's phase lock loop will remain locked for less rf power. The initial test results of the piezo tuner will be presented. |
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THP022 | SC Nb Sputtered QWRs for the REX-ISOLDE Accelerator at CERN: Prototype Design and Manufacturing | cavity, linac, vacuum, simulation | 827 |
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The HIE-ISOLDE activity aims at the construction of a superconducting linac based on 101.28 MHz Nb sputtered Quarter Wave Resonators (QWRs), which will be installed downstream the present REX-ISOLDE linac. The present design considers two basic geometries of the cavities (geometric β0 = 6.26% and 10.84%) for which a mechanical, chemical treatment and Nb coating design study has been performed. We report here on the status of the prototype cavity and sputtering tests. |
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THP025 | Superconducting Quarter-Wave Resonators for the ATLAS Energy Upgrade | cavity, cryomodule, linac, coupling | 836 |
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A set of six new 109 MHz β=0.15 superconducting quarter-wave resonators (QWR) has been built at ANL as part of an upgrade to the ATLAS superconducting heavy-ion linac. The final cavity string assembly will also use many of the techniques needed for the next generation of large high-performance ion linacs such as the U.S. Department of Energy's FRIB project. Single-cavity cold tests at T=4.5 K have been performed for three cavities with moveable coupler, rf pickup, and VCX fast tuner as required for the full 6-meter cryomodule assembly. The average maximum accelerating gradient of 4 cavities (3 new + 1 prototype), is EACC=11.2 MV/m (BPEAK=65 mT). Clean cavity string assembly techniques, required here and for most future SRF ion linacs, are fairly well developed. Details on cavity performance including high-field cw operation, microphonics and fast tuning are presented. |
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THP026 | Surface Processing Facilities for Superconducting RF Cavities at ANL | cavity, linac, controls, cathode | 839 |
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New SRF cavity processing systems at ANL, including those for electropolishing (EP), high-pressure water rinsing (HPR), and single-cavity clean room assembly have been developed and operated at ANL for use with cavities for a range of electron and ion linac applications. Jointly with FNAL, systems for 1.3 GHz single- and multi-cell elliptical cavities for the linear collider effort have been developed. New systems for use with low-beta TEM-class cavities have also been built and used to process a set of new quarter-wave resonators as part of an upgrade to the ATLAS heavy-ion accelerator at ANL. All of the new hardware is located in a 200 m2 joint ANL/FNAL Superconducting Cavity Surface Process Facility (SCSPF) consisting of two separate chemical processing rooms, a clean anteroom, and a pair of class 10 and 100 clean rooms for HPR and clean assembly. Results of first cold tests for elliptical and TEM-class cavities processed in these facilities are presented. |
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THP042 | High-Gradient SRF R&D for ILC at Jefferson Lab | cavity, SRF, cathode, instrumentation | 879 |
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Funding: Supported by DOE |
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THP043 | Preliminary Results from Multi-Cell Seamless Niobium Cavities Fabricated by Hydroforming | cavity, cryogenics, vacuum, electron | 882 |
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Funding: This manuscript has been partially authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177. |
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THP093 | Power Coupler and Tuner Development for Superconducting Quarter-Wave Resonators | vacuum, cavity, cryomodule, superconductivity | 1005 |
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The construction of a reaccelerator for secondary ion beams is currently underway at the National Superconducting Cyclotron Laboratory (NSCL). The reaccelerator linac will use superconducting quarter-wave resonators (QWR) operating at 80.5 MHz with beta = 0.041 and beta = 0.085. A coaxial probe-type rf fundamental power coupler (FPC) will be used for both QWR types. The power coupler makes use of a commercially-available feedthrough to minimize the cost. The FPC has been simulated and optimized for operation at 80.5 MHz using a finite element electromagnetics code. Prototype FPC have been fabricated and conditioned with traveling wave and standing wave power using a 1 kW amplifier. A niobium tuning plate is incorporated into the bottom flange of the QWR. The tuner is actuated by a stepping motor for slow (coarse) tuning and a stacked piezoelectric element in series for fast (fine) tuning. A prototype tuner for the beta = 0.041 QWR has been tested on the cavity at room temperature. This paper will cover the design, fabrication, and testing of the prototype coupler and tuner. |