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Experiences with the Fermilab HINS 325 MHz RFQ  [PDF]
R. C. Webber,T. Khabiboulline,R. Madrak,G. Romanov,V. Scarpine,J. Steimel,D. Wildman
Physics , 2012,
Abstract: The Fermilab High Intensity Neutrino Source program has built and commissioned a pulsed 325 MHz RFQ. The RFQ has successfully accelerated a proton beam at the RFQ design RF power. Experiences encountered during RFQ conditioning, including the symptoms and cause of a run-away detuning problem, and the first beam results are first reported.
Design of a 325MHz Half Wave Resonator prototype at IHEP  [PDF]
Xinying Zhang,Weimin Pan,Guangwei Wang,Bo Xu,Guangyuan Zhao,Feisi He,Zhongquan Li,Qiang Ma,Jin Dai,Xu Chen,Yaping Liu,Zhou Xue,Xuefang Huang,Yi Sun
Physics , 2015,
Abstract: A 325MHz beta=0.14 superconducting half wave resonator(HWR) prototype has been developed at the Institute of High Energy Physics(IHEP), which can be applied in continuous wave (CW) high beam proton accelerators. In this paper, the electromagnetic (EM) design, multipacting simulation, mechanical optimization, and fabrication are introduced in details. In vertical test at 4.2K, the cavity reached Eacc=7MV/m with Q0=1.4*10^9 and Eacc=15.9MV/m with Q0=4.3*10^8.
Design of a 325MHz SC Spoke040 cavity at IHEP  [PDF]
Peng Yinghua,Zhang Xinying,Sha Peng,Pan Weimin,Li Han
Physics , 2013,
Abstract: The 325MHz, {\beta}=0.40 superconducting single spoke cavity (Spoke040) was one of the most challenges for the China-ADS (Accelerator Driven System) project. The design was finished, and the fabrication was in progressing. In this paper, we studied the main radio frequency (RF) and mechanical parameters, and compared the arc-shaped and plate-shaped end group structures.
Design of a 325MHz Beta=0.12 superconducting single spoke cavity for China-ADS  [PDF]
Han Li,Jianping Dai,Peng Sha,Hong Huang,Qunyao Wang,juan Zhang,Zhongyuan Yao,Xiangyang Lu
Physics , 2013, DOI: 10.1088/1674-1137/38/7/077008
Abstract: Twelve superconducting single spoke cavities whose Beta is 0.12 (Spoke012) operating at 325MHz, are adopted in Injector I for China-ADS linac. This type of spoke cavity is believed to be one of the key challenges for its very low geometry Beta. So far, the prototype cavity has been designed, fabricated and tested successfully. The design work was finished by using CST-MWS and ANSYS software for the RF and mechanical properties optimization. This paper presents the details of the final design for Spoke012 prototype cavity.
First high power pulsed tests of a dressed 325 MHz superconducting single spoke resonator at Fermilab  [PDF]
R. Madrak,J. Branlard,B. Chase,C. Darve,P. Joireman,T. Khabiboulline,A. Mukherjee,T. Nicol,E. Peoples-Evans,D. Peterson,Y. Pischalnikov,L. Ristori,W. Schappert,D. Sergatskov,W. Soyars,J. Steimel,I. Terechkine,V. Tupikov,R. Wagner,R. C. Webber,D. Wildman
Physics , 2012,
Abstract: In the recently commissioned superconducting RF cavity test facility at Fermilab (SCTF), a 325 MHz, {\beta}=0.22 superconducting single-spoke resonator (SSR1) has been tested for the first time with its input power coupler. Previously, this cavity had been tested CW with a low power, high Qext test coupler; first as a bare cavity in the Fermilab Vertical Test Stand and then fully dressed in the SCTF. For the tests described here, the design input coupler with Qext ~ 106 was used. Pulsed power was provided by a Toshiba E3740A 2.5 MW klystron.
First high gradient test results of a dressed 325 MHz superconducting single spoke resonator at Fermilab  [PDF]
R. C. Webber,T. Khabiboulline,R. Madrak,T. Nicol,L. Ristori,W. Soyars,R. Wagner
Physics , 2012,
Abstract: A new superconducting RF cavity test facility has been commissioned at Fermilab in conjunction with first tests of a 325 MHz, {\beta} = 0.22 superconducting single-spoke cavity dressed with a helium jacket and prototype tuner. The facility is described and results of full gradient, CW cavity tests with a high Qext drive coupler are reported. Sensitivities to Q disease and externally applied magnetic fields were investigated. Results are compared to bare cavity results obtained prior to hydrogen degassing and welding into the helium jacket.
325mhz超导腔输入耦合器镀铜层厚度的实验研究  [PDF]
强激光与粒子束 , 2014,
Abstract: ?通过对工作在325mhz、镀铜厚度分别为10,20,30μm的耦合器外导体进行高功率测试,研究了超导腔输入耦合器外导体内壁镀铜层厚度与漏热的依赖关系,目的在于寻找最优化的铜层厚度来降低超导腔输入耦合器的低温漏热。实验结果表明,20μm铜层的耦合器具有较低的动态损耗。综合考虑静态损耗与动态损耗,则20μm铜层厚度为最优化的铜层厚度。
A 325-MHz GMRT survey of the Herschel-ATLAS/GAMA fields  [PDF]
T. Mauch,H. -R. Kl?ckner,S. Rawlings,M. J. Jarvis,M. J. Hardcastle,D. Obreschkow,D. J. Saikia,M. A. Thompson
Physics , 2013, DOI: 10.1093/mnras/stt1323
Abstract: We describe a 325-MHz survey, undertaken with the Giant Metrewave Radio Telescope (GMRT), which covers a large part of the three equatorial fields at 9, 12 and 14.5 h of right ascension from the Herschel-Astrophysical Terahertz Large Area Survey (H-ATLAS) in the area also covered by the Galaxy And Mass Assembly survey (GAMA). The full dataset, after some observed pointings were removed during the data reduction process, comprises 212 GMRT pointings covering ~90 deg^2 of sky. We have imaged and catalogued the data using a pipeline that automates the process of flagging, calibration, self-calibration and source detection for each of the survey pointings. The resulting images have resolutions of between 14 and 24 arcsec and minimum rms noise (away from bright sources) of ~1 mJy/beam, and the catalogue contains 5263 sources brighter than 5 sigma. We investigate the spectral indices of GMRT sources which are also detected at 1.4 GHz and find them to agree broadly with previously published results; there is no evidence for any flattening of the radio spectral index below S_1.4=10 mJy. This work adds to the large amount of available optical and infrared data in the H-ATLAS equatorial fields and will facilitate further study of the low-frequency radio properties of star formation and AGN activity in galaxies out to z~1.
325mhz低β半波长谐振腔设计  [PDF]
强激光与粒子束 , 2013,
Abstract: ?对质子加速器中半波长谐振腔(hwr)型的设计进行了研究,完成一种新型hwr超导腔的初步设计。通过对超导腔设计方法及设计原则的研究,结合相关半波长谐振腔的研究现状,充分利用电磁设计软件的功能,对325mhz低β大孔径的半波长谐振腔进行了设计研究。在建模中,针对腔体的不同部位进行比较分析,优化模型形状;在计算中,采用新型有限元网格,使计算快速而结果稳定;在后处理中,使用参数扫描,实现了腔形参数优化;在腔形分析中,计算了二次电子倍增效应,验证了腔体形状的可行性。通过此设计过程,使所设计的新型β为0.12的hwr腔具有较好的电磁参数,满足质子加速器的要求,并可应用到实际工程中。
325 MHz VLA Observations of Ultracool Dwarfs TVLM 513-46546 and 2MASS J0036+1821104  [PDF]
T. R. Jaeger,R. A. Osten,T. J. Lazio,N. Kassim,R. L. Mutel
Physics , 2011, DOI: 10.1088/0004-6256/142/6/189
Abstract: We present 325 MHz (90 cm wavelength) radio observations of ultracool dwarfs TVLM 513-46546 and 2MASS J0036+1821104 using the Very Large Array (VLA) in June 2007. Ultracool dwarfs are expected to be undetectable at radio frequencies, yet observations at 8.5 GHz (3.5 cm) and 4.9 GHz (6 cm) of have revealed sources with > 100 {\mu}Jy quiescent radio flux and > 1 mJy pulses coincident with stellar rotation. The anomalous emission is likely a combination of gyrosynchrotron and cyclotron maser processes in a long-duration, large-scale magnetic field. Since the characteristic frequency for each process scales directly with the magnetic field magnitude, emission at lower frequencies may be detectable from regions with weaker field strength. We detect no significant radio emission at 325 MHz from TVLM 513-46546 or 2MASS J0036+1821104 over multiple stellar rotations, establishing 2.5{\sigma} total flux limits of 795 {\mu}Jy and 942 {\mu}Jy respectively. Analysis of an archival VLA 1.4 GHz observation of 2MASS J0036+1821104 from January 2005 also yields a non-detection at the level of < 130 {\mu}Jy . The combined radio observation history (0.3 GHz to 8.5 GHz) for these sources suggests a continuum emission spectrum for ultracool dwarfs which is either flat or inverted below 2-3 GHz. Further, if the cyclotron maser instability is responsible for the pulsed radio emission observed on some ultracool dwarfs, our low-frequency non-detections suggest that the active region responsible for the high-frequency bursts is confined within 2 stellar radii and driven by electron beams with energies less than 5 keV.
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