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Romanov, G.

Paper Title Page
TPPP053 Thin RF Windows for High-Pressure Gas-Filled Cavities 3224
 
  • M. Alsharo'a, R.P. Johnson
    Muons, Inc, Batavia
  • M. Gosz, D.M. Kaplan, S. Nair
    Illinois Institute of Technology, Chicago, Illinois
  • A. Moretti, G. Romanov
    Fermilab, Batavia, Illinois
 
  Funding: This work was supported in part by DOE STTR grant DE-FG02-02ER86145.

RF cavities for muon ionization cooling channels can have RF windows over their ends to create better internal voltage profiles and to make them independent of each other. To be effective, the conducting window material must be sufficiently transparent to the muons to not affect the beam cooling, which means low mass and low Z. In the case of pressurized RF cavities, as to opposed to those that operate in vacuum, the RF window design is simplified because the heat deposited in the windows from the RF and the beam is carried off by the hydrogen gas. In this report we analyze the thermal, mechanical, and electrical properties of a simple beryllium grid structure to improve the performance of pressurized RF cavities that are to be used for muon beam cooling.

 
ROAA005 Recent Innovations in Muon Beam Cooling and Prospects for Muon Colliders 419
 
  • R.P. Johnson, M. Alsharo'a, P.M. Hanlet, R. E. Hartline, M. Kuchnir, K. Paul, T.J. Roberts
    Muons, Inc, Batavia
  • C.M. Ankenbrandt, E. Barzi, L. DelFrate, I.G. Gonin, A. Moretti, D.V. Neuffer, M. Popovic, G. Romanov, D. Turrioni, V. Yarba
    Fermilab, Batavia, Illinois
  • K. Beard, S.A. Bogacz, Y.S. Derbenev
    Jefferson Lab, Newport News, Virginia
  • D.M. Kaplan, K. Yonehara
    Illinois Institute of Technology, Chicago, Illinois
 
  Funding: This work was supported in part by DOE SBIR/STTR grants DE-FG02-02ER86145, 03ER83722, 04ER84015, 04ER86191, and 04ER84016.

A six-dimensional(6D)cooling channel based on helical magnets surrounding RF cavities filled with dense hydrogen gas* is used to achieve the small transverse emittances demanded by a high-luminosity muon collider. This helical cooling channel**(HCC) has solenoidal, helical dipole, and helical quadrupole magnetic fields to generate emittance exchange. Simulations verify the analytic predictions and have shown a 6D emittance reduction of over 3 orders of magnitude in a 100 m HCC segment. Using three such sequential HCC segments, where the RF frequencies are increased and transverse dimensions reduced as the beams become cooler, implies a 6D emittance reduction of almost six orders of magnitude. After this, two new post-cooling ideas can be employed to reduce transverse emittances to one or two mm-mr, which allows high luminosity with fewer muons than previously imagined. In this report we discuss the status of and the plans for the HCC simulation and engineering efforts. We also describe the new post-cooling ideas and comment on the prospects for a Higgs factory or energy frontier muon collider using existing laboratory infrastructure.

*R. P. Johnson et al. LINAC2004, www.muonsinc.com/TU203.pdf. **Y. Derbenev and R.P. Johnson, Submitted to PRSTAB, http://www-mucool.fnal.gov/mcnotes/public/pdf/muc0284/muc0284.pdf.

 
ROAC004 High Gradient Performance of NLC/GLC X-Band Accelerating Structures 372
 
  • S. Doebert, C. Adolphsen, G.B. Bowden, D.L. Burke, J. Chan, V.A. Dolgashev, J.C. Frisch, R.K. Jobe, R.M. Jones, R.E. Kirby, J.R. Lewandowski, Z. Li, D.J. McCormick, R.H. Miller, C.D. Nantista, J. Nelson, C. Pearson, M.C. Ross, D.C. Schultz, T.J. Smith, S.G. Tantawi, J.W. Wang
    SLAC, Menlo Park, California
  • T.T. Arkan, C. Boffo, H. Carter, I.G. Gonin, T.K. Khabiboulline, S.C. Mishra, G. Romanov, N. Solyak
    Fermilab, Batavia, Illinois
  • Y. Funahashi, H. Hayano, N. Higashi, Y. Higashi, T. Higo, H. Kawamata, T. Kume, Y. Morozumi, K. Takata, T. T. Takatomi, N. Toge, K. Ueno, Y. Watanabe
    KEK, Ibaraki
 
  Funding: Work Supported by DOE Contract DE-AC02-76F00515.

During the past five years, there has been an concerted effort at FNAL, KEK and SLAC to develop accelerator structures that meet the high gradient performance requirements for the Next Linear Collider (NLC) and Global Linear Collider (GLC) initiatives. The structure that resulted is a 60-cm-long, traveling-wave design with low group velocity (< 4% c) and a 150 degree phase advance per cell. It has an average iris size that produces an acceptable short-range wakefield in the linacs, and dipole mode damping and detuning that adequately suppresses the long-range wakefield. More than eight such structures have operated over 1000 hours at a 60 Hz pulse rate at the design gradient (65 MV/m) and pulse length (400 ns), and have reached breakdown rate levels below the limit for the linear collider. Moreover, the structures are robust in that the breakdown rates continue to decrease over time, and if the structures are briefly exposed to air, the rates recover to their low values within a few days. This paper presents a final summary of the results from this program, which effectively ended last August with the selection of ‘cold’ technology for a next generation linear collider.

 
FPAE054 Front End Design of a Multi-GeV H-minus Linac 3286
 
  • P.N. Ostroumov, K.W. Shepard
    ANL, Argonne, Illinois
  • G.W. Foster, I.G. Gonin, G. Romanov
    Fermilab, Batavia, Illinois
 
  Funding: This work was supported by the U.S. Department of Energy under Contracts No. W-31-109-ENG-38 and DE-AC02-76CH03000.

The proposed 8-GeV driver at FNAL is based on ~480 independently phased SC resonators. Significant cost saving is expected by using an rf power fan out from high-power klystrons to multiple cavities. Successful development of superconducting (SC) multi-spoke resonators operating at ~345-350 MHz provides a strong basis for their application in the front end of multi-GeV linear accelerators. Such a front-end operating at 325 MHz would enable direct transition to high-gradient 1300 MHz SC TESLA-style cavities at ~400 MeV. The proposed front end consists of 5 sections: a conventional RFQ, room-temperature (RT) cross-bar H-type (CH) cavities, single-, double- and triple-spoke superconducting resonators. For several reasons which are discussed in this paper there is a large advantage in using independently phased RT CH-cavities between the RFQ and SC sections in the energy range 3-15 MeV.