Plasma Outages in Pulsed, High-Power RF Hydrogen Ion Sources

ORAL

Abstract

Pulsed, high-power RF ion sources are needed to produce copious amounts of negative H- ions for high-power accelerators with charge-changing injection schemes. When increasing the RF power, the plasma inductance changes the RF resonance, which drifts away from the low-power resonance. When the RF circuit is tuned to maximize the (pulsed) plasma power, the (off- resonance) power at the beginning of the pulse is reduced. If the induced electric fields fall below the breakdown strength of the hydrogen gas, the plasma fails to develop. This can be avoided with a compromise tune and/or by increasing the inductance of the resonant circuit. However, the breakdown strength of the hydrogen gas increases with time due to the gradual decrease of the electron-rich plasma impurities, which causes plasma outages after weeks of reliable operation. In this paper we discuss the success of different mitigations that were tested and implemented to overcome this fundamental problem of pulsed, high-power RF hydrogen ion sources.

Authors

  • Martin Stockli

    Oak Ridge National Laboratory

  • Baoxi Han

    Oak Ridge National Laboratory

  • Syd Murray

    Oak Ridge National Laboratory

  • Terry Pennisi

    Oak Ridge National Laboratory

  • Chip Piller

    Oak Ridge National Laboratory

  • Manuel Santana

    Oak Ridge National Laboratory

  • Antony Valentini

    CITA, MIT, Caltech/JPL, Academia Sinica, Dong Hwa Univ., Soochow Univ., Nanticoke High School, UT, Maverick Systems Corp., RIS Corp., LSU, Shimadzu Corp., UNIRIB, ORAU/ORISE, Physics Division, Oak Ridge National Laboratory, Oak Ridge Associated Universities, Los Alamos National Laboratory, University of South Dakota, RIKEN BNL Research Center, University of Wisconsin-Milwaukee, Brown University, University of Maryland, Jet Propulsion Laboratory - California Institute of Technology, Center for Relativistic Astrophysics, Georgia Tech, University of Rochester, University of Idaho, Texas A\&M University, Universit\'e Paris Diderot-Paris 7, Washington University in St. Louis, Harvard-Smithsonian Center for Astrophysics, University of California, Berkeley, Massachusetts Institute of Technology, Rockwell Collins Inc., Northwestern University, N IST, Indiana Unviersity, Harvard University, University of Notre Dame, Fachbereich Theoretische Physik, Institut fur Physik, Karl-Franzens-Universitat Graz, Austria, Instituto de Estructura de la Materia, CSIC, Spain, Physics Department, University of Wisconsin-Barron, Orion Foundation, Physics Dept, University of West Florida, Pensacola, Florida, 32514, TUNL, Duke University, James Madison University, University of New Mexico, Photonics CoE, Idaho State University, Pocatello, ID 83209, Los Alamos National Laboratory, Los Alamos, NM 87545, Argonne National Laboratory, University of Washington, National Institute of Standards and Technology, National Institute of Standards and Technology (and West Virginia University), NRAO, University of Florida, LLNL / NPS, LLNL, UC Berkeley, LLNL/NPS, Univerity of Washington, CNRS-IN2P3, Marseille, FR, CERN and King's College, London UK, Brookhaven National Laboratory, ICTP, Trieste, IT, Fermi National Accelerator Laboratory, University of Wisconsin Milwaukee, Princeton University, North Carolina Central U. (NCCU), Triangle Universities Nuclear Laboratory (TUNL), University of California, Riverside, NSCL/MSU, Triangle Universities Nuclear Laboratory, Duke University, University of North Carolina, Duke University, University of North Carolina at Chapel Hill, Triangle Universities Nuclear Laboratory, KVI Groningen, APS Director of Public Affairs, Perimeter Institute, Caltech, Rutgers, U. Tenn., ORNL, Stanford School of Medicine, Radiation Oncology and Molecular Imaging Program, Stanford Applied Physics Department, Stanford School of Medicine, Radiation Oncology, Boston University, BNL, Rutgers University, Purdue University, Penn. State University, UCSD, Lawrence Livermore National Laboratory, University of Richmond, University of Massachusetts-Lowell, Mississippi State University, University of Tennessee, Argonne National Lab, Florida State University, US Naval Academy, ANL, Univ. of Maryland, Univ. of Massachusetts (Lowell), Univ. of Tennessee, Univ. of Manchester, UK, NBI, Danmark, Mississippi State Univ., Physics Division, Argonne National Laboratory, Argonne, IL 60439, Mississippi State University, Mississippi State, MS 39762, UGC-DAE Consortium for Science Research, Kolkata, India, Department of Physics, University of Notre Dame, Notre Dame, IN 46556, San Jose State University, Pacific Northwest National Laboratory, University of Chicago, Fermilab, Program Director, US LHC Accelerator Research Program (LARP), Montana State University, Department of Astrophysical Sciences, Princeton University, School of Mathematics, University of Southampton, CCT, Louisiana State University, CSIC-IEEC Barcelona, TAPIR, California Institute of Technology, University of Texas at Brownsville, Royal Military College of Canada, California State University, Sacramento, Norfolk State University, Oak Ridge National Laboratory, Utah State University, Executive Producer \& Co-Creator of The Big Bang Theory, University of California, Los Angeles, Cyclotron Institute, Texas A\&M University, Hope College, NSCL, Augustana College, Clemson University