| Paper |
Title |
Page |
| MOPCH178 |
Tests on MgB2 for Application to SRF Cavities
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481 |
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- T. Tajima
LANL, Los Alamos, New Mexico
- I.E. Campisi
ORNL, Oak Ridge, Tennessee
- A. Canabal-Rey
NMSU, Las Cruces, New Mexico
- Y. Iwashita
Kyoto ICR, Uji, Kyoto
- B. Moeckly
STI, Santa Barbara, California
- C.D. Nantista, S.G. Tantawi
SLAC, Menlo Park, California
- H.L. Phillips
Jefferson Lab, Newport News, Virginia
- A.S. Romanenko
Cornell University, Laboratory for Elementary-Particle Physics, Ithaca, New York
- Y. Zhao
University of Wollongong, Institute of Superconducting and Electronic Materials, Wollongong
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Magnesium diboride (MgB2) has a transition temperature (Tc) of ~40 K, i.e., about four times higher than niobium (Nb). The studies in the last three years have shown that it could have about one order of magnitude less RF surface resistance (Rs) than Nb and seems much less power dependent compared to high-Tc materials such as YBCO. In this paper we will present results on the dependence of Rs on surface magnetic fields and possibly the critical RF surface magnetic field.
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| MOPCH184 |
Plasma Treatment of Bulk Niobium Surfaces for SRF Cavities
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493 |
| |
- L. Vuskovic, S. Popovic, M. Raskovic
ODU, Norfolk, Virginia
- L. Godet, S.B. Radovanov
VSEA, Gloucester, Maryland
- H.L. Phillips, A-M. Valente-Feliciano
Jefferson Lab, Newport News, Virginia
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Cavity surface preparation has been one of the major problems in superconducting radio-frequency (SRF) accelerator technology. Accelerator performance depends directly on the physical and chemical characteristics at the SRF cavity surface. The primary objective of our work is to explore the effects of various types of electric discharge plasmas to minimize surface roughness and eliminate or minimize deterioration of cavity properties by oxygen, hydrogen and other chemical contaminants. To optimize the plasma etching process, samples of bulk Nb are being exposed to three types of electrical discharge in various experimental set-ups. The surface quality obtained by the three methods was compared with samples treated with buffer chemical polishing techniques. Surface comparisons are made using digital imaging (optical) microscopy, scanning electron microscopy, and atomic force microscopy. In preliminary tests, samples compared with those treated conventionally have shown comparable or superior properties. Tests have also shown that surface quality varies with plasma conditions and their optimization to obtain the best SRF cavity surface is a major goal of the ongoing work.
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| TUPCH148 |
201 MHz Cavity R&D for MUCOOL and MICE
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1367 |
| |
- D. Li, S.P. Virostek, M.S. Zisman
LBNL, Berkeley, California
- A. Bross, A. Moretti, B. Norris
Fermilab, Batavia, Illinois
- J. Norem
ANL, Argonne, Illinois
- H.L. Phillips, R.A. Rimmer, M. Stirbet
Jefferson Lab, Newport News, Virginia
- M. Reep, D.J. Summers
UMiss, University, Mississippi
- Y. Torun
IIT, Chicago, Illinois
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We describe the design, fabrication and preliminary testing of the prototype 201 MHz copper cavity for a muon ionization cooling channel. Application of the cavity includes the Muon Ionization Cooling Experiment (MICE) as well as cooling channels for a neutrino factory or a muon collider. This cavity was developed by the US MUCOOL collaboration and is being tested in the MUCOOL Test Area (MTA) at Fermilab. In order to achieve a high accelerating gradient, the cavity beam irises are terminated by a pair of curved, thin beryllium windows. Several of the fabrication methods developed for this cavity and the windows are novel and offer significant cost savings compared to conventional construction methods. Cavity thermal and RF performance will be compared to FEA modeling predictions. RF commissioning results will be presented.
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