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Zhao, Y.

Paper Title Page
TPPE042 Study of Secondary Emission Enhanced Photoinjector 2711
 
  • X.Y. Chang, I. Ben-Zvi, A. Burrill, P.D.J. Johnson, J. Kewisch, T. Rao, Z. Segalov, Y. Zhao
    BNL, Upton, Long Island, New York
 
  The secondary emission enhanced photoinjector (SEEP) is a very promising new approach to the generation of high-current, high-brightness electron beams. Primary electrons with a few thousand electron-volts of energy strike a specially prepared diamond window. The large Secondary Electron Yield (SEY) provides a multiplication of the number of electrons by about two orders of magnitude. The secondary electrons drift through the diamond under an electric field and emerge into the accelerating proper of the “gun” through a Negative Electron Affinity (NEA) surface of the diamond (Hydrogen terminated). We present the calculation of heating power sources and the temperature distribution in details. Some properties of the secondary electron beam related to beam dynamics are also reported. The results show feasibility of this kind of cathode.  
TPPE061 RF Design and Operating Performance of the BNL/AES 1.3 GHz Single Cell Superconducting RF Photocathode Electron Gun 3514
 
  • M.D. Cole
    AES, Medford, NY
  • I. Ben-Zvi, A. Burrill, H. Hahn, T. Rao, Y. Zhao
    BNL, Upton, Long Island, New York
  • P. Kneisel
    Jefferson Lab, Newport News, Virginia
 
  Over the past several years Advanced Energy Systems and BNL have been collaborating on the development and testing of a fully superconducting photocathode electron gun. Over the past year we have begun to realize significant results which have been published elsewhere.* This paper will review the RF design of the gun under test and present results of its performance under various operating conditions. Results for cavity quality factor will be presented for various operating temperatures and cavity field gradients. We will discuss various methods of determining the cavity fields and the extent of agreement between them. We will also discuss future plans for testing using this gun.

*Photoemission studies on BNL/AES all niobium, Superconducting RF injector, T. Rao, these proceedings.

 
WPAP038 Photoemission Studies on BNL/AES/JLab all Niobium, Superconducting RF Injector 2556
 
  • T. Rao, I. Ben-Zvi, A. Burrill, H. Hahn, D. Kayran, Y. Zhao
    BNL, Upton, Long Island, New York
  • M.D. Cole
    AES, Medford, NY
  • P. Kneisel
    Jefferson Lab, Newport News, Virginia
 
  Funding: Under contract with the U.S. DOE, Contract No. DE-AC02-98CH10886.

Photoemission from all niobium superconducting injector is of considerable interest for the development of higher average current electron sources. In the past year, we have generated photocurrent from such an injector by irradiating the back wall of the 1/2 cell cavity with 248 nm and 266 nm laser beams. In this paper, we present the results of these measurements including the quantum efficiency, and its dependence on the field and wavelength. Issues related to the quenching of the cavity by the laser radiation will also be addressed.

 
WPAT049 The Penetrability of a Thin Metallic Film Inside the RF Field 3073
 
  • Y. Zhao, I. Ben-Zvi, R.H. Beuttenmuller, X.Y. Chang, C. Chen, R. Di Nardo, T. Rao
    BNL, Upton, Long Island, New York
 
  Funding: Under contract with the U.S. Department of Energy, Contract Number DE-AC02-98CH10886.

Thin metallic film was widely applied in varies area. Especially, recently we are planning to apply it in a "Secondary emission enhanced photo-injector," of which a diamond cathode is coated with a golden film or so on its back to serve as a current path. The thickness of the film is originally considered to be in the order of 10 nm, which is much less than the skin depth, say 1/200. Since it is so thin, that intuitively the RF filed is penetrable. However, we found it is not true. The film will block most of the field. This paper addresses theoretic analysis as well as the experimental results. All demonstrated that the penetrability of a thin film is very poor. Consequently, most of the RF current will flow on the thin film causing a serous heating problem.

 
TPAP043 Electron Cooling of RHIC 2741
 
  • I. Ben-Zvi, D.S. Barton, D.B. Beavis, M. Blaskiewicz, J.M. Brennan, A. Burrill, R. Calaga, P. Cameron, X.Y. Chang, R. Connolly, Yu.I. Eidelman, A.V. Fedotov, W. Fischer, D.M. Gassner, H. Hahn, M. Harrison, A. Hershcovitch, H.-C. Hseuh, A.K. Jain, P.D.J. Johnson, D. Kayran, J. Kewisch, R.F. Lambiase, V. Litvinenko, W.W. MacKay, G.J. Mahler, N. Malitsky, G.T. McIntyre, W. Meng, K.A.M. Mirabella, C. Montag, T.C.N. Nehring, T. Nicoletti, B. Oerter, G. Parzen, D. Pate, J. Rank, T. Rao, T. Roser, T. Russo, J. Scaduto, K. Smith, D. Trbojevic, G. Wang, J. Wei, N.W.W. Williams, K.-C. Wu, V. Yakimenko, A. Zaltsman, Y. Zhao
    BNL, Upton, Long Island, New York
  • D.T. Abell, D.L. Bruhwiler
    Tech-X, Boulder, Colorado
  • H. Bluem, A. Burger, M.D. Cole, A.J. Favale, D. Holmes, J. Rathke, T. Schultheiss, A.M.M. Todd
    AES, Princeton, New Jersey
  • A.V. Burov, S. Nagaitsev
    Fermilab, Batavia, Illinois
  • J.R. Delayen, Y.S. Derbenev, L. W. Funk, P. Kneisel, L. Merminga, H.L. Phillips, J.P. Preble
    Jefferson Lab, Newport News, Virginia
  • I. Koop, V.V. Parkhomchuk, Y.M. Shatunov, A.N. Skrinsky
    BINP SB RAS, Novosibirsk
  • I.N. Meshkov, A.O. Sidorin, A.V. Smirnov, G.V. Troubnikov
    JINR, Dubna, Moscow Region
  • J.S. Sekutowicz
    DESY, Hamburg
 
  We report progress on the R&D program for electron-cooling of the Relativistic Heavy Ion Collider (RHIC). This electron cooler is designed to cool 100 GeV/nucleon at storage energy using 54 MeV electrons. The electron source will be a superconducting RF photocathode gun. The accelerator will be a superconducting energy recovery linac. The frequency of the accelerator is set at 703.75 MHz. The maximum electron bunch frequency is 9.38 MHz, with bunch charge of 20 nC. The R&D program has the following components: The photoinjector and its photocathode, the superconducting linac cavity, start-to-end beam dynamics with magnetized electrons, electron cooling calculations including benchmarking experiments and development of a large superconducting solenoid. The photoinjector and linac cavity are being incorporated into an energy recovery linac aimed at demonstrating ampere class current at about 20 MeV. A Zeroth Order Design Report is in an advanced draft state, and can be found on the web at http://www.agsrhichome.bnl.gov/eCool/.

Under contract with the U.S. Department of Energy, Contract Number DE-AC02-98CH10886.

 
WPAP033 State-of-the-Art Electron Guns and Injector Designs for Energy Recovery Linacs (ERL) 2292
 
  • A.M.M. Todd, A. Ambrosio, H. Bluem, V. Christina, M.D. Cole, M. Falletta, D. Holmes, E. Peterson, J. Rathke, T. Schultheiss, R. Wong
    AES, Medford, NY
  • I. Ben-Zvi, A. Burrill, R. Calaga, P. Cameron, X.Y. Chang, H. Hahn, D. Kayran, J. Kewisch, V. Litvinenko, G.T. McIntyre, T. Nicoletti, J. Rank, T. Rao, J. Scaduto, K.-C. Wu, A. Zaltsman, Y. Zhao
    BNL, Upton, Long Island, New York
  • S.V. Benson, E. Daly, D. Douglas, H.F.D. Dylla, L. W. Funk, C. Hernandez-Garcia, J. Hogan, P. Kneisel, J. Mammosser, G. Neil, H.L. Phillips, J.P. Preble, R.A. Rimmer, C.H. Rode, T. Siggins, T. Whitlach, M. Wiseman
    Jefferson Lab, Newport News, Virginia
  • I.E. Campisi
    ORNL, Oak Ridge, Tennessee
  • P. Colestock, J.P. Kelley, S.S. Kurennoy, D.C. Nguyen, W. Reass, D. Rees, S.J. Russell, D.L. Schrage, R.L. Wood
    LANL, Los Alamos, New Mexico
  • D. Janssen
    FZR, Dresden
  • J.W. Lewellen
    ANL, Argonne, Illinois
  • J.S. Sekutowicz
    DESY, Hamburg
  • L.M. Young
    TechSource, Santa Fe, New Mexico
 
  Funding: This work is supported by NAVSEA, NSWC Crane, the Office of Naval Research, the DOD Joint Technology Office and by the U.S. DOE.

A key technology issue of ERL devices for high-power free-electron laser (FEL) and 4th generation light sources is the demonstration of reliable, high-brightness, high-power injector operation. Ongoing programs that target up to 1 Ampere injector performance at emittance values consistent with the requirements of these applications are described. We consider that there are three possible approaches that could deliver the required performance. The first is a DC photocathode gun and superconducting RF (SRF) booster cryomodule. Such a 750 MHz device is being integrated and will be tested up to 100 mA at the Thomas Jefferson National Accelerator Facility beginning in 2007. The second approach is a high-current normal-conducting RF photoinjector. A 700 MHz gun will undergo thermal test in 2006 at the Los Alamos National Laboratory, which, if successful, when equipped with a suitable cathode, would be capable of 1 Ampere operation. The last option is an SRF gun. A half-cell 703 MHz SRF gun capable of delivering 1.0 Ampere will be tested to 0.5 Ampere at the Brookhaven National Laboratory in 2006. The fabrication status, schedule and projected performance for each of these state-of-the-art injector programs will be presented.

 
RPPE032 Measurement of the Secondary Emission Yield of a Thin Diamond Window in Transmission Mode 2251
 
  • X.Y. Chang, I. Ben-Zvi, A. Burrill, S. Hulbert, P.D.J. Johnson, J. Kewisch, T. Rao, Z. Segalov, J. Smedley, Y. Zhao
    BNL, Upton, Long Island, New York
 
  The secondary emission enhanced photoinjector (SEEP) is a promising new approach to the generation of high-current, high-brightness electron beams. A low current primary electron beam with energy of a few thousand electron-volts strikes a specially prepared diamond window which emits secondary electrons with a current two orders of magnitude higher. The secondary electrons are created at the back side of the diamond and drift through the window under the influence of a strong electrical field. A hydrogen termination at the exit surface of the window creates a negative electron affinity (NEA) which allows the electrons to leave the diamond. An experiment was performed to measure the secondary electron yield and other properties. The results are discussed in this paper.  
RPPE009 Extremely High Current, High-Brightness Energy Recovery Linac 1150
 
  • I. Ben-Zvi, D.S. Barton, D.B. Beavis, M. Blaskiewicz, J.M. Brennan, A. Burrill, R. Calaga, P. Cameron, X.Y. Chang, R. Connolly, D.M. Gassner, J.G. Grimes, H. Hahn, A. Hershcovitch, H.-C. Hseuh, P.D.J. Johnson, D. Kayran, J. Kewisch, R.F. Lambiase, V. Litvinenko, G.T. McIntyre, W. Meng, T.C.N. Nehring, T. Nicoletti, B. Oerter, D. Pate, J. Rank, T. Rao, T. Roser, T. Russo, J. Scaduto, Z. Segalov, K. Smith, N.W.W. Williams, K.-C. Wu, V. Yakimenko, K. Yip, A. Zaltsman, Y. Zhao
    BNL, Upton, Long Island, New York
  • H. Bluem, A. Burger, M.D. Cole, A.J. Favale, D. Holmes, J. Rathke, T. Schultheiss, A.M.M. Todd
    AES, Princeton, New Jersey
  • J.R. Delayen, L. W. Funk, P. Kneisel, H.L. Phillips, J.P. Preble
    Jefferson Lab, Newport News, Virginia
 
  Funding: Under contract with the U.S. Department of Energy, U.S. DOD Office of Naval Research and Joint Technology Office.

Next generation ERL light-sources, high-energy electron coolers, high-power Free-Electron Lasers, powerful Compton X-ray sources and many other accelerators were made possible by the emerging technology of high-power, high-brightness electron beams. In order to get the anticipated performance level of ampere-class currents, many technological barriers are yet to be broken. BNL’s Collider-Accelerator Department is pursuing some of these technologies for its electron cooling of RHIC application, as well as a possible future electron-hadron collider. We will describe work on CW, high-current and high-brightness electron beams. This will include a description of a superconducting, laser-photocathode RF gun and an accelerator cavity capable of producing low emittance (about 1 micron rms normalized) one nano-Coulomb bunches at currents of the order of one ampere average.

 
RPPT032 High Current Energy Recovery Linac at BNL 2242
 
  • V. Litvinenko, D.B. Beavis, I. Ben-Zvi, M. Blaskiewicz, J.M. Brennan, A. Burrill, R. Calaga, P. Cameron, X.Y. Chang, R. Connolly, D.M. Gassner, H. Hahn, A. Hershcovitch, H.-C. Hseuh, P.D.J. Johnson, D. Kayran, J. Kewisch, R.F. Lambiase, G.J. Mahler, G.T. McIntyre, W. Meng, T.C.N. Nehring, T. Nicoletti, B. Oerter, D. Pate, J. Rank, T. Rao, T. Roser, T. Russo, J. Scaduto, K. Smith, N.W.W. Williams, K.-C. Wu, V. Yakimenko, K. Yip, A. Zaltsman, Y. Zhao
    BNL, Upton, Long Island, New York
  • H. Bluem, A. Burger, M.D. Cole, A.J. Favale, D. Holmes, J. Rathke, T. Schultheiss, A.M.M. Todd
    AES, Princeton, New Jersey
  • J.R. Delayen, L. W. Funk, H.L. Phillips, J.P. Preble
    Jefferson Lab, Newport News, Virginia
 
  Funding: Work performed under Contract Number DE-AC02-98CH10886 with the auspices of the U.S. Department of Energy.

We present the design and the parameters of a small Energy Recovery Linac (ERL) facility, which is under construction at BNL. This R&D facility has goals to demonstrate CW operation of ERL with average beam current in the range of 0.1 - 1 ampere, combined with very high efficiency of energy recovery. The possibility for future up-grade to a two-pass ERL is being considered. The heart of the facility is a 5-cell 703.75 MHz super-conducting RF linac with HOM damping. Flexible lattice of ERL provides a test-bed for testing issues of transverse and longitudinal instabilities and diagnostics of intense CW e-beam. We present the status and plans for this facility.