Effect of multiphoton ionization in laser Thomson scattering measurements

POSTER

Abstract

In laser Thomson scattering measurements of electron density and temperature, one should be careful about production of electrons in the scattering volume via laser irradiation. It is generally assumed that Ar plasma is free from such laser perturbations. However, in our measurements for inductively coupled Ar plasma using a frequency-doubled YAG laser (532 nm), Thomson scattering spectra obtained from measurements with different laser energy densities at the focal point differ significantly, when the discharge power is low and hence the ratio of the metastable Ar atom density to the electron density is relatively large. This suggests that multiphoton ionization of metastable Ar atoms may affect the measurement significantly. To clarify the phenomenon, an experiment for determining the ionization yield at the laser focal point in the Ar gas containing a known concentration of metastable Ar atoms is being carried out. The laser beam is focused at the center of a small dc-biased parallel-plate probe and the laser-induced probe current is measured. Preliminary measurements indicate successful detection of the current due to multiphoton ionization of metastable Ar atoms, the efficiency of which is to be quantified. (Work supported by Grant-in-aid 18540491 from MEXT Japan.)

Authors

  • A. Kono

    Nagoya University

  • John B. Boffard

    Nagoya University, Nagoya Univ., NU-Eco Eng, Meijo Univ., Aichi Inst. Tech., Tohoku Univ., Univ.of Tokyo, Saitama Univ., Saitama Small Enterprise Prom. Corp., Dept. of Biomed. Eng., Musashi Inst. of Technol., Air Force Research Laboratory, WPAFB, OH, WVU, Morgantown, WV, Department of Physics, Old Dominion University, Technische Universiteit Eindhoven, Institut f\'ur Niedertemperatur Plasmaphysik, Greifswald, Germany, Eindhoven University of Technology, Eindhoven, The Netherlands, Dept. of Physics, Sardar Patel University, Vallabh Vidyanagar, School of EPS - Chemistry, Heriot-Watt University, UK, School of Pharmacy and iEPSAM, Keele University, UK, School of Pharmacy, University of Nottingham, UK, Plasma \& Surface Analysis Division, Hiden Analytical Ltd., UK, Institute of Physics, Belgrade, Serbia, School of Electrical Engineering, Belgrade, Serbia, Katagiri Engineering, Meijo University, Dong-A University, UES, Dayton, OH, AFRL, Wright-Patterson AFB, OH, St. Petersburg State University, St. Petersburg, Russia, West Virginia University, Charles University in Prague, Institute of Physics of the Academy of Sciences of the Czech Republic, v. v. i., USTHB, LECTCM, PO. Box 32 El Alia, BabEzzouar, Algiers, Algeria, CDTA, Department of Physics, Old Dominion University, Norfolk, VA, Air Force Research Laboratory, Wright-Patterson AFB, OH, Innovative Scientific Solutions, Inc., Dayton, OH, Department of Physics, KAIST and Courant Institute, NYU, Department of Physics, KAIST, Centre for Antimatter-Matter Studies, Australian National University, Canberra, Centre for Antimatter-Matter Studies, SoCPES, Flinders University, Adelaide, Australia, Center for Plasma Science and Technology, Ruhr University Bochum, Germany, University of Missouri-Rolla, Los Alamos National Laboratory, Australian National University, Max-Planck-Institute for Nuclear Physics, Applied Materials, Sandia National Laboratories, Lam Research Corporation, UC Berkeley, Prometheus Energy Company, Army Research Laboratory, Smithsonian Astrophysical Observatory, University of Pittsburgh, University of Wisconsin-Madison, Berkeley Research Associates, Commonwealth Technologies, Inc., Naval Research Laboratory, Philips Lighting (CDL), Eindhoven, The Netherlands, Sekisui Chemical Co., Ltd., Faculty of Systems Engineering, Wakayama University, Department of Electrical Engineering, Nagoya University, Ruhr-University Bochum, Germany, Queens University Belfast, Northern Ireland, Katagiri Engineering Co., Ltd., NU EcoEngineering Co., Ltd., NU System Co., Ltd., Wakayama University, Department of Physics, California State University, Fullerton, CA 92834, USA, Jet Propulsion Laboratory, Caltech, MS 183-601, 4800 Oak Grove Drive, Pasadena, CA 91109, USA, Old Dominion University, NIE and Institute of Advanced Studies, Nanyang Technological University, The University of Texas at Austin, Department of Physics, Indian Institute of Technology, Roorkee - 247667, India, Tokyo Institute of Technology, Ruhr-University Bochum, 44780 Bochum, Germany, University of Antwerpen, B-2020 Antwerpen, Belgium, Institute of Theoretical and Applied Mechanics, 630090 Novosibirsk, Russia, Tokyo Electron, Hokkaido University, OSRAM GmbH, Munich, Germany, INP Greifswald, Germany, Departamento de Fisica, Universidade da Madeira, Largo do Municipio, 9000 Funchal, Portugal, Ruhr-University Bochum, RSPhysSE, ANU, Australia, Ruhr University Bochum, Germany, Queen's University Belfast, Northern Ireland, Ecole Polytechnique, France, Nanotechnology Research Institute, University of Ulster, Newtownabbey, Institute for Plasma and Atomic Physics, Ruhr-University Bochum, Germany, DF, UM, Braga, Auburn University, Research group PLASMANT, Dep. of Chemistry, University of Antwerp, Belgium, Open University, University of Glasgow, Dept. of Physics \& Astronomy, Kelvin Building, University of Glasgow, G12 8QQ, UK, EM2C, Ecole Centrale, LPTP, Ecole Polytechnique, France, State University, St Petersburg, INP-Greifswald, Ecole Polytechnique, Queen`s University Belfast, Institute of Physics Belgrade, University of Ulster, University of Duisburg-Essen, Applied Materials, Inc., LPTP, Ecole Polytechnique, Kyoto University, Center for Plasma Science and Technology, Ruhr-Universtity Bochum, Germany, Centre for Plasma Physics, Queen's University Belfast, Northern Ireland, University of Minnesota, Dublin City University, Institute for Theoretical Electrical Engineering, Ruhr-University Bochum, Institute for Plasma and Atomic Physics, Ruhr-University Bochum, National Centre for Plasma Science and Technology, Dublin City University, Ireland, Centre for Plasma Science and Technology, Ruhr University Bochum, Germany, University of Manchester

  • John B. Boffard

    Nagoya University, Nagoya Univ., NU-Eco Eng, Meijo Univ., Aichi Inst. Tech., Tohoku Univ., Univ.of Tokyo, Saitama Univ., Saitama Small Enterprise Prom. Corp., Dept. of Biomed. Eng., Musashi Inst. of Technol., Air Force Research Laboratory, WPAFB, OH, WVU, Morgantown, WV, Department of Physics, Old Dominion University, Technische Universiteit Eindhoven, Institut f\'ur Niedertemperatur Plasmaphysik, Greifswald, Germany, Eindhoven University of Technology, Eindhoven, The Netherlands, Dept. of Physics, Sardar Patel University, Vallabh Vidyanagar, School of EPS - Chemistry, Heriot-Watt University, UK, School of Pharmacy and iEPSAM, Keele University, UK, School of Pharmacy, University of Nottingham, UK, Plasma \& Surface Analysis Division, Hiden Analytical Ltd., UK, Institute of Physics, Belgrade, Serbia, School of Electrical Engineering, Belgrade, Serbia, Katagiri Engineering, Meijo University, Dong-A University, UES, Dayton, OH, AFRL, Wright-Patterson AFB, OH, St. Petersburg State University, St. Petersburg, Russia, West Virginia University, Charles University in Prague, Institute of Physics of the Academy of Sciences of the Czech Republic, v. v. i., USTHB, LECTCM, PO. Box 32 El Alia, BabEzzouar, Algiers, Algeria, CDTA, Department of Physics, Old Dominion University, Norfolk, VA, Air Force Research Laboratory, Wright-Patterson AFB, OH, Innovative Scientific Solutions, Inc., Dayton, OH, Department of Physics, KAIST and Courant Institute, NYU, Department of Physics, KAIST, Centre for Antimatter-Matter Studies, Australian National University, Canberra, Centre for Antimatter-Matter Studies, SoCPES, Flinders University, Adelaide, Australia, Center for Plasma Science and Technology, Ruhr University Bochum, Germany, University of Missouri-Rolla, Los Alamos National Laboratory, Australian National University, Max-Planck-Institute for Nuclear Physics, Applied Materials, Sandia National Laboratories, Lam Research Corporation, UC Berkeley, Prometheus Energy Company, Army Research Laboratory, Smithsonian Astrophysical Observatory, University of Pittsburgh, University of Wisconsin-Madison, Berkeley Research Associates, Commonwealth Technologies, Inc., Naval Research Laboratory, Philips Lighting (CDL), Eindhoven, The Netherlands, Sekisui Chemical Co., Ltd., Faculty of Systems Engineering, Wakayama University, Department of Electrical Engineering, Nagoya University, Ruhr-University Bochum, Germany, Queens University Belfast, Northern Ireland, Katagiri Engineering Co., Ltd., NU EcoEngineering Co., Ltd., NU System Co., Ltd., Wakayama University, Department of Physics, California State University, Fullerton, CA 92834, USA, Jet Propulsion Laboratory, Caltech, MS 183-601, 4800 Oak Grove Drive, Pasadena, CA 91109, USA, Old Dominion University, NIE and Institute of Advanced Studies, Nanyang Technological University, The University of Texas at Austin, Department of Physics, Indian Institute of Technology, Roorkee - 247667, India, Tokyo Institute of Technology, Ruhr-University Bochum, 44780 Bochum, Germany, University of Antwerpen, B-2020 Antwerpen, Belgium, Institute of Theoretical and Applied Mechanics, 630090 Novosibirsk, Russia, Tokyo Electron, Hokkaido University, OSRAM GmbH, Munich, Germany, INP Greifswald, Germany, Departamento de Fisica, Universidade da Madeira, Largo do Municipio, 9000 Funchal, Portugal, Ruhr-University Bochum, RSPhysSE, ANU, Australia, Ruhr University Bochum, Germany, Queen's University Belfast, Northern Ireland, Ecole Polytechnique, France, Nanotechnology Research Institute, University of Ulster, Newtownabbey, Institute for Plasma and Atomic Physics, Ruhr-University Bochum, Germany, DF, UM, Braga, Auburn University, Research group PLASMANT, Dep. of Chemistry, University of Antwerp, Belgium, Open University, University of Glasgow, Dept. of Physics \& Astronomy, Kelvin Building, University of Glasgow, G12 8QQ, UK, EM2C, Ecole Centrale, LPTP, Ecole Polytechnique, France, State University, St Petersburg, INP-Greifswald, Ecole Polytechnique, Queen`s University Belfast, Institute of Physics Belgrade, University of Ulster, University of Duisburg-Essen, Applied Materials, Inc., LPTP, Ecole Polytechnique, Kyoto University, Center for Plasma Science and Technology, Ruhr-Universtity Bochum, Germany, Centre for Plasma Physics, Queen's University Belfast, Northern Ireland, University of Minnesota, Dublin City University, Institute for Theoretical Electrical Engineering, Ruhr-University Bochum, Institute for Plasma and Atomic Physics, Ruhr-University Bochum, National Centre for Plasma Science and Technology, Dublin City University, Ireland, Centre for Plasma Science and Technology, Ruhr University Bochum, Germany, University of Manchester