Modeling of the ``death-ray'' phenomenon in tokamak edge

POSTER

Abstract

In the ``death-ray'' regime often seen in tokamak edge plasma experiments, the downstream electron pressure, as measured by Langmuir probes at the divertor plate, exceeds the upstream values by nearly a factor of 2 over a narrow radial region at the strike point [1,2]. However, recent studies on Alcator C-Mod indicate that the death-ray over-pressure may be a result of local plasma perturbation by the negative probe bias [3]. We investigate the effects of probe perturbation of the plasma using the tokamak edge fluid code UEDGE. The code models a slab-like configuration roughly matching the basic dimensions and characteristics of edge plasma in Alcator C-Mod near detachment, where the death-ray is often observed. In the code setup, a small axisymmetric segment of target plate is biased, which mimics a plate-mounted Langmuir probe. It is observed in the simulations that at sufficiently large negative bias voltage the probe substantially modifies the local plasma characteristics. Moreover, the simulations reproduce the overpressure along the field line, similar to the experimental death-ray; pointing to the interplay of ion-neutral momentum exchange and the sheath boundary conditions [4].\\[4pt] [1] D. Brunner et al., APS DPP 2010, poster TP9.00069;\\[0pt] [2] B. LaBombard et al., J. Nucl. Mater. 241-243, 149-166 (1997);\\[0pt] [3] A. Loarte et al., Nucl. Fusion 38, 331 (1998);\\[0pt] [4] M.V. Umansky et al., Contrib. Plasma Phys., accepted (2011).

Authors

  • M.V. Umansky

    Lawrence Livermore National Laboratory, LLNL, Lawrence Livermore National Lab

  • Ozgur Erken

    NASA Glenn Research Center, Indiana University - Bloomington, Wayne State University, FermiLab, Northwestern University, MIT, Fermilab, RAL, Vilnius University, University of Nebraska - Lincoln, California Institute of Technology, University of Maryland, Los Alamos National Laboratory, General Atomics, University of Washington, University of Tulsa, Columbia University, University of Bologna and INFN-Bologna, Italy, University of New Mexico, Rice University, University of Bologna, Department of Physics, Montana State University, Departamento de Matematicas, Universidad de San Carlos, TAPIR, California Institute of Technology, Brown University, Perimeter Institute, University of Guelph, Louisana State University, Universidad Michoacana de San Nicolas de Hidalgo, Canadian Institute for Theoretical Astrophysics, Cornell University, Louisiana State University, Universidad Michoacana de San Nicol\'as de Hidalgo, University of Chicago, Universita` di Roma II ``Tor Vergata'' and Sezione INFN, Roma, Italy, Argonne National Laboratory, Argonne, Universidade Federal do Rio de Janeiro, Instituto de Fisica, Rio de Janeiro, Brazil, University of Hawaii at Manoa, Fermilab, Batavia, IL, USA, Dipartimento di Fisica dell'Universita` del Salento and Sezione INFN, Lecce, Italy, Institute of Physics, Academy of Sciences of the Czech Republic, Prague, Czech Republic, University of Wisconsin - Madison Department of Physics, University of Florida, Clark Atlanta University, The Center of Physics and Chemistry of Materials, Fisk University, University of Pennsylvania, The University of South Carolina, University of Virginia, Florida Institute of Technology, ANL and Northwestern University, California State University, Fresno, Department of Astronomy and Astrophysics, Kavli Institute for Cosmological Physics, The University of Chicago, Theoretical Astrophysics, California Institute of Technology, University of Saskatchewan, Institute of Physics, University of San Paulo, San Paulo, Brazil, Univ Calif San Diego, MIT PSFC, PPPL, LLNL, Massachusetts Institute of Technology, UCSD, K.U. Leuven, ITER Organization, University of Wisconsin-Madison, LBNL, University of California Irvine, Tech-X Corp. and University of Colorado at Boulder, UC Berkeley and LBNL, UCSD and SciberQuest, Inc, Universidad Politecnica de Madrid, Culham Sci. Ctr, Tech-X Corporation, Utah State University, University of Wisconsin - Madison, Princeton Plasma Physics Lab, University of Maryland, College Park, Max Planck Institute for Plasma Physics, Greifswald, Princeton Plasma Physics Laboratory, MIT Plasma Science and Fusion Center, International Institute for Fusion Science, University of Texas at Austin, University of Wisconsin, Science Education Department, Harvard Smithsonian Center for Astrophysics, Department of Engineering \& Science Education, Clemson University, Department of Engineering \& Science Education and Department of Mathematical Sciences, Clemson University, Curry School of Education, University of Virginia, Harvard-Smithsonian Center for Astrophysics, Science Education Department, Department of Engineering and Science Education and Department of Mathematical Sciences, Clemson University, Science Education Department, Harvard-Smithsonian Center for Astrophysics, Oak Ridge National Laboratory, St Mary's College of Maryland, The University of Mississippi, Caltech, Cornell, National Institute for Theoretical Physics, Stellenbosch, South Africa, MPI Hannover, University of Birmingham, Cardiff University, University of Maryland - College Park, IPPCAS, Carleton University, Indiana University, Centre for High Energy Physics, Punjab U, Lahore, Pakistan, CITA, University of Toronto, Goldsmiths, University of London, Georgia Tech, Rutgers University, Regis University, University of South Dakota, Florida State University, Department of Physics, University of Washington, Seattle, WA 98195-1560, USA, Max-Planck-Institute for Nuclear Physics, Heidelberg, Germany, Universidad de la Republica Oriental del Uruguay, Jet Propulsion Laboratory, California Institute of Technology, University of Minnesota, NASA/Goddard Space Flight Center, Washington University in Saint Louis, JPL/Caltech, Washington University in St. Louis, Washington University, Department of Physics, Indiana University Bloomington, Department of Physics, North Carolina State University, Raleigh, North Carolina 27695-8202, Department of Physics, Teachers College, Kyungpook National University, Daegu, Korea 702-701, Oakland University, University of Michigan, Argonne National Laboratory, University of Kentucky, Georgia State University, The College of New Jersey, NASA/JPL, Space Science Institute, KI (Ru), University of California, San Diego, University of Texas, Austin, NTUA, Athens, Greece, UCLA, U. Alberta, EPFL,Lausanne,Switzerland, University of Rochester, University of Colorado at Boulder, U. of California, Berkeley, National Radio Astronomy Observatory, U. of Florida, Naval Postgraduate School, Lawrence Livermore National Laboratory, U. of Washington, Humboldt State University, Princeton University, U Texas-Austin, NAOJ, Cornell University, Washington State University, University of Wisconsin-Milwaukee, University of Illinois, Friedrich-Schiller University Jena, Centre de Recherches en Physique des Plasmas (CRPP), Lausanne, Switzerland, SUNY at Buffalo, Cyclotron Institute, Texas A\&M University, Texas A\&M University, Texas A\&M University and University of Athens, Texas A\&M University and LNS INFN, University of Massachusetts-Lowell, Mississippi State University, University of Notre Dame, University of Tennessee, US Naval Academy, Univ. of Massachusetts-Lowell, Mississippi State Univ., Univ. of Notre Dame, Argonne National Lab, Univ. of Tennessee, Florida State Univ., Lund University, United States Naval Academy, Argonne National Laboratory/University of Maryland, University of Liverpool, STFC Daresbury Laboratory, Lawrence Berkeley National Laboratory, Vanderbilt University, UNIRIB/Oak Ridge Associated Universities, Peking University, Tsinghua University, Kings College, University of Wiskonsin-Milwaukee, NASA Goddard Space Flight Center, University of Illinois Urbana-Champaign, Montana State University, Rochester Institute of Technology, Johns Hopkins University, Lawrenceville School, University of California, Berkeley, The University of Tennessee Space Institute, Department of Physics and Astronomy, Georgia State University, Atlanta, GA, Department of Physics, University of West Georgia, Carrollton GA, Institute for Microstructural Sciences, National Research Council, Canada, School of Electronic and Electrical Engineering, University of Leeds, UK, Harvard University, Purdue University, Haverford College, Clemson University, Francis Marion University, Armstrong Atlantic State University, Western Kentucky University, Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, Central Arizona College, Coolidge, Arizona, John Hopkins University Applied Physics,Laurel, Maryland, John Hopkins University, Baltimore, Maryland, Southwest Research Institute, San Antonio, Texas, Southwest Research Institute, Boulder, Colorado, HPI; Spacetime Inst., JPL-Caltech, University of Kansas, Naval Research Lab, University of California Berkeley, Yale, Old Dominion University, McGill University, Virginia Tech, Brookhaven National Lab, Thomas Jefferson National Accelerator Facility, Lawrence Livermore Nat Lab and University of California Davis, University of Massachusetts Amherst, APC, Univ Paris Diderot, Sungkyunkwan University, Korea, Czech Technical University in Prague, Czech Republic, Georgia Institute of Technology, Society of Physics Students / Drury University, Joint Institute for Nuclear Research, Ecopulse, Inc., US Army Research Laboratory, Drexel University, Yale University, New Haven, CT, DePaul University, Chicago, IL, Rutgers University, Piscataway, NJ, Millsaps College, Jackson, MS, University of Bonn, retired, ANL and U. of Notre Dame, IFJ PAN, ANL, U. of Maryland, U. of Maryland and ANL, Chemistry Department, Washington University, Physics Department Florida State University, Tulane University / Los Alamos National Laboratory, National Institute of Standards and Technology, University of Tennessee / Oak Ridge National Laboratory, Department of Applied Physics, Polytechnic Institute of NYU

  • Ozgur Erken

    NASA Glenn Research Center, Indiana University - Bloomington, Wayne State University, FermiLab, Northwestern University, MIT, Fermilab, RAL, Vilnius University, University of Nebraska - Lincoln, California Institute of Technology, University of Maryland, Los Alamos National Laboratory, General Atomics, University of Washington, University of Tulsa, Columbia University, University of Bologna and INFN-Bologna, Italy, University of New Mexico, Rice University, University of Bologna, Department of Physics, Montana State University, Departamento de Matematicas, Universidad de San Carlos, TAPIR, California Institute of Technology, Brown University, Perimeter Institute, University of Guelph, Louisana State University, Universidad Michoacana de San Nicolas de Hidalgo, Canadian Institute for Theoretical Astrophysics, Cornell University, Louisiana State University, Universidad Michoacana de San Nicol\'as de Hidalgo, University of Chicago, Universita` di Roma II ``Tor Vergata'' and Sezione INFN, Roma, Italy, Argonne National Laboratory, Argonne, Universidade Federal do Rio de Janeiro, Instituto de Fisica, Rio de Janeiro, Brazil, University of Hawaii at Manoa, Fermilab, Batavia, IL, USA, Dipartimento di Fisica dell'Universita` del Salento and Sezione INFN, Lecce, Italy, Institute of Physics, Academy of Sciences of the Czech Republic, Prague, Czech Republic, University of Wisconsin - Madison Department of Physics, University of Florida, Clark Atlanta University, The Center of Physics and Chemistry of Materials, Fisk University, University of Pennsylvania, The University of South Carolina, University of Virginia, Florida Institute of Technology, ANL and Northwestern University, California State University, Fresno, Department of Astronomy and Astrophysics, Kavli Institute for Cosmological Physics, The University of Chicago, Theoretical Astrophysics, California Institute of Technology, University of Saskatchewan, Institute of Physics, University of San Paulo, San Paulo, Brazil, Univ Calif San Diego, MIT PSFC, PPPL, LLNL, Massachusetts Institute of Technology, UCSD, K.U. Leuven, ITER Organization, University of Wisconsin-Madison, LBNL, University of California Irvine, Tech-X Corp. and University of Colorado at Boulder, UC Berkeley and LBNL, UCSD and SciberQuest, Inc, Universidad Politecnica de Madrid, Culham Sci. Ctr, Tech-X Corporation, Utah State University, University of Wisconsin - Madison, Princeton Plasma Physics Lab, University of Maryland, College Park, Max Planck Institute for Plasma Physics, Greifswald, Princeton Plasma Physics Laboratory, MIT Plasma Science and Fusion Center, International Institute for Fusion Science, University of Texas at Austin, University of Wisconsin, Science Education Department, Harvard Smithsonian Center for Astrophysics, Department of Engineering \& Science Education, Clemson University, Department of Engineering \& Science Education and Department of Mathematical Sciences, Clemson University, Curry School of Education, University of Virginia, Harvard-Smithsonian Center for Astrophysics, Science Education Department, Department of Engineering and Science Education and Department of Mathematical Sciences, Clemson University, Science Education Department, Harvard-Smithsonian Center for Astrophysics, Oak Ridge National Laboratory, St Mary's College of Maryland, The University of Mississippi, Caltech, Cornell, National Institute for Theoretical Physics, Stellenbosch, South Africa, MPI Hannover, University of Birmingham, Cardiff University, University of Maryland - College Park, IPPCAS, Carleton University, Indiana University, Centre for High Energy Physics, Punjab U, Lahore, Pakistan, CITA, University of Toronto, Goldsmiths, University of London, Georgia Tech, Rutgers University, Regis University, University of South Dakota, Florida State University, Department of Physics, University of Washington, Seattle, WA 98195-1560, USA, Max-Planck-Institute for Nuclear Physics, Heidelberg, Germany, Universidad de la Republica Oriental del Uruguay, Jet Propulsion Laboratory, California Institute of Technology, University of Minnesota, NASA/Goddard Space Flight Center, Washington University in Saint Louis, JPL/Caltech, Washington University in St. Louis, Washington University, Department of Physics, Indiana University Bloomington, Department of Physics, North Carolina State University, Raleigh, North Carolina 27695-8202, Department of Physics, Teachers College, Kyungpook National University, Daegu, Korea 702-701, Oakland University, University of Michigan, Argonne National Laboratory, University of Kentucky, Georgia State University, The College of New Jersey, NASA/JPL, Space Science Institute, KI (Ru), University of California, San Diego, University of Texas, Austin, NTUA, Athens, Greece, UCLA, U. Alberta, EPFL,Lausanne,Switzerland, University of Rochester, University of Colorado at Boulder, U. of California, Berkeley, National Radio Astronomy Observatory, U. of Florida, Naval Postgraduate School, Lawrence Livermore National Laboratory, U. of Washington, Humboldt State University, Princeton University, U Texas-Austin, NAOJ, Cornell University, Washington State University, University of Wisconsin-Milwaukee, University of Illinois, Friedrich-Schiller University Jena, Centre de Recherches en Physique des Plasmas (CRPP), Lausanne, Switzerland, SUNY at Buffalo, Cyclotron Institute, Texas A\&M University, Texas A\&M University, Texas A\&M University and University of Athens, Texas A\&M University and LNS INFN, University of Massachusetts-Lowell, Mississippi State University, University of Notre Dame, University of Tennessee, US Naval Academy, Univ. of Massachusetts-Lowell, Mississippi State Univ., Univ. of Notre Dame, Argonne National Lab, Univ. of Tennessee, Florida State Univ., Lund University, United States Naval Academy, Argonne National Laboratory/University of Maryland, University of Liverpool, STFC Daresbury Laboratory, Lawrence Berkeley National Laboratory, Vanderbilt University, UNIRIB/Oak Ridge Associated Universities, Peking University, Tsinghua University, Kings College, University of Wiskonsin-Milwaukee, NASA Goddard Space Flight Center, University of Illinois Urbana-Champaign, Montana State University, Rochester Institute of Technology, Johns Hopkins University, Lawrenceville School, University of California, Berkeley, The University of Tennessee Space Institute, Department of Physics and Astronomy, Georgia State University, Atlanta, GA, Department of Physics, University of West Georgia, Carrollton GA, Institute for Microstructural Sciences, National Research Council, Canada, School of Electronic and Electrical Engineering, University of Leeds, UK, Harvard University, Purdue University, Haverford College, Clemson University, Francis Marion University, Armstrong Atlantic State University, Western Kentucky University, Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, Central Arizona College, Coolidge, Arizona, John Hopkins University Applied Physics,Laurel, Maryland, John Hopkins University, Baltimore, Maryland, Southwest Research Institute, San Antonio, Texas, Southwest Research Institute, Boulder, Colorado, HPI; Spacetime Inst., JPL-Caltech, University of Kansas, Naval Research Lab, University of California Berkeley, Yale, Old Dominion University, McGill University, Virginia Tech, Brookhaven National Lab, Thomas Jefferson National Accelerator Facility, Lawrence Livermore Nat Lab and University of California Davis, University of Massachusetts Amherst, APC, Univ Paris Diderot, Sungkyunkwan University, Korea, Czech Technical University in Prague, Czech Republic, Georgia Institute of Technology, Society of Physics Students / Drury University, Joint Institute for Nuclear Research, Ecopulse, Inc., US Army Research Laboratory, Drexel University, Yale University, New Haven, CT, DePaul University, Chicago, IL, Rutgers University, Piscataway, NJ, Millsaps College, Jackson, MS, University of Bonn, retired, ANL and U. of Notre Dame, IFJ PAN, ANL, U. of Maryland, U. of Maryland and ANL, Chemistry Department, Washington University, Physics Department Florida State University, Tulane University / Los Alamos National Laboratory, National Institute of Standards and Technology, University of Tennessee / Oak Ridge National Laboratory, Department of Applied Physics, Polytechnic Institute of NYU

  • Ozgur Erken

    NASA Glenn Research Center, Indiana University - Bloomington, Wayne State University, FermiLab, Northwestern University, MIT, Fermilab, RAL, Vilnius University, University of Nebraska - Lincoln, California Institute of Technology, University of Maryland, Los Alamos National Laboratory, General Atomics, University of Washington, University of Tulsa, Columbia University, University of Bologna and INFN-Bologna, Italy, University of New Mexico, Rice University, University of Bologna, Department of Physics, Montana State University, Departamento de Matematicas, Universidad de San Carlos, TAPIR, California Institute of Technology, Brown University, Perimeter Institute, University of Guelph, Louisana State University, Universidad Michoacana de San Nicolas de Hidalgo, Canadian Institute for Theoretical Astrophysics, Cornell University, Louisiana State University, Universidad Michoacana de San Nicol\'as de Hidalgo, University of Chicago, Universita` di Roma II ``Tor Vergata'' and Sezione INFN, Roma, Italy, Argonne National Laboratory, Argonne, Universidade Federal do Rio de Janeiro, Instituto de Fisica, Rio de Janeiro, Brazil, University of Hawaii at Manoa, Fermilab, Batavia, IL, USA, Dipartimento di Fisica dell'Universita` del Salento and Sezione INFN, Lecce, Italy, Institute of Physics, Academy of Sciences of the Czech Republic, Prague, Czech Republic, University of Wisconsin - Madison Department of Physics, University of Florida, Clark Atlanta University, The Center of Physics and Chemistry of Materials, Fisk University, University of Pennsylvania, The University of South Carolina, University of Virginia, Florida Institute of Technology, ANL and Northwestern University, California State University, Fresno, Department of Astronomy and Astrophysics, Kavli Institute for Cosmological Physics, The University of Chicago, Theoretical Astrophysics, California Institute of Technology, University of Saskatchewan, Institute of Physics, University of San Paulo, San Paulo, Brazil, Univ Calif San Diego, MIT PSFC, PPPL, LLNL, Massachusetts Institute of Technology, UCSD, K.U. Leuven, ITER Organization, University of Wisconsin-Madison, LBNL, University of California Irvine, Tech-X Corp. and University of Colorado at Boulder, UC Berkeley and LBNL, UCSD and SciberQuest, Inc, Universidad Politecnica de Madrid, Culham Sci. Ctr, Tech-X Corporation, Utah State University, University of Wisconsin - Madison, Princeton Plasma Physics Lab, University of Maryland, College Park, Max Planck Institute for Plasma Physics, Greifswald, Princeton Plasma Physics Laboratory, MIT Plasma Science and Fusion Center, International Institute for Fusion Science, University of Texas at Austin, University of Wisconsin, Science Education Department, Harvard Smithsonian Center for Astrophysics, Department of Engineering \& Science Education, Clemson University, Department of Engineering \& Science Education and Department of Mathematical Sciences, Clemson University, Curry School of Education, University of Virginia, Harvard-Smithsonian Center for Astrophysics, Science Education Department, Department of Engineering and Science Education and Department of Mathematical Sciences, Clemson University, Science Education Department, Harvard-Smithsonian Center for Astrophysics, Oak Ridge National Laboratory, St Mary's College of Maryland, The University of Mississippi, Caltech, Cornell, National Institute for Theoretical Physics, Stellenbosch, South Africa, MPI Hannover, University of Birmingham, Cardiff University, University of Maryland - College Park, IPPCAS, Carleton University, Indiana University, Centre for High Energy Physics, Punjab U, Lahore, Pakistan, CITA, University of Toronto, Goldsmiths, University of London, Georgia Tech, Rutgers University, Regis University, University of South Dakota, Florida State University, Department of Physics, University of Washington, Seattle, WA 98195-1560, USA, Max-Planck-Institute for Nuclear Physics, Heidelberg, Germany, Universidad de la Republica Oriental del Uruguay, Jet Propulsion Laboratory, California Institute of Technology, University of Minnesota, NASA/Goddard Space Flight Center, Washington University in Saint Louis, JPL/Caltech, Washington University in St. Louis, Washington University, Department of Physics, Indiana University Bloomington, Department of Physics, North Carolina State University, Raleigh, North Carolina 27695-8202, Department of Physics, Teachers College, Kyungpook National University, Daegu, Korea 702-701, Oakland University, University of Michigan, Argonne National Laboratory, University of Kentucky, Georgia State University, The College of New Jersey, NASA/JPL, Space Science Institute, KI (Ru), University of California, San Diego, University of Texas, Austin, NTUA, Athens, Greece, UCLA, U. Alberta, EPFL,Lausanne,Switzerland, University of Rochester, University of Colorado at Boulder, U. of California, Berkeley, National Radio Astronomy Observatory, U. of Florida, Naval Postgraduate School, Lawrence Livermore National Laboratory, U. of Washington, Humboldt State University, Princeton University, U Texas-Austin, NAOJ, Cornell University, Washington State University, University of Wisconsin-Milwaukee, University of Illinois, Friedrich-Schiller University Jena, Centre de Recherches en Physique des Plasmas (CRPP), Lausanne, Switzerland, SUNY at Buffalo, Cyclotron Institute, Texas A\&M University, Texas A\&M University, Texas A\&M University and University of Athens, Texas A\&M University and LNS INFN, University of Massachusetts-Lowell, Mississippi State University, University of Notre Dame, University of Tennessee, US Naval Academy, Univ. of Massachusetts-Lowell, Mississippi State Univ., Univ. of Notre Dame, Argonne National Lab, Univ. of Tennessee, Florida State Univ., Lund University, United States Naval Academy, Argonne National Laboratory/University of Maryland, University of Liverpool, STFC Daresbury Laboratory, Lawrence Berkeley National Laboratory, Vanderbilt University, UNIRIB/Oak Ridge Associated Universities, Peking University, Tsinghua University, Kings College, University of Wiskonsin-Milwaukee, NASA Goddard Space Flight Center, University of Illinois Urbana-Champaign, Montana State University, Rochester Institute of Technology, Johns Hopkins University, Lawrenceville School, University of California, Berkeley, The University of Tennessee Space Institute, Department of Physics and Astronomy, Georgia State University, Atlanta, GA, Department of Physics, University of West Georgia, Carrollton GA, Institute for Microstructural Sciences, National Research Council, Canada, School of Electronic and Electrical Engineering, University of Leeds, UK, Harvard University, Purdue University, Haverford College, Clemson University, Francis Marion University, Armstrong Atlantic State University, Western Kentucky University, Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, Central Arizona College, Coolidge, Arizona, John Hopkins University Applied Physics,Laurel, Maryland, John Hopkins University, Baltimore, Maryland, Southwest Research Institute, San Antonio, Texas, Southwest Research Institute, Boulder, Colorado, HPI; Spacetime Inst., JPL-Caltech, University of Kansas, Naval Research Lab, University of California Berkeley, Yale, Old Dominion University, McGill University, Virginia Tech, Brookhaven National Lab, Thomas Jefferson National Accelerator Facility, Lawrence Livermore Nat Lab and University of California Davis, University of Massachusetts Amherst, APC, Univ Paris Diderot, Sungkyunkwan University, Korea, Czech Technical University in Prague, Czech Republic, Georgia Institute of Technology, Society of Physics Students / Drury University, Joint Institute for Nuclear Research, Ecopulse, Inc., US Army Research Laboratory, Drexel University, Yale University, New Haven, CT, DePaul University, Chicago, IL, Rutgers University, Piscataway, NJ, Millsaps College, Jackson, MS, University of Bonn, retired, ANL and U. of Notre Dame, IFJ PAN, ANL, U. of Maryland, U. of Maryland and ANL, Chemistry Department, Washington University, Physics Department Florida State University, Tulane University / Los Alamos National Laboratory, National Institute of Standards and Technology, University of Tennessee / Oak Ridge National Laboratory, Department of Applied Physics, Polytechnic Institute of NYU