Study on argon metastable and 4p state neutral atoms in magnetized ICP and Helicon plasmas measured by Laser Induced Fluorescence and plasma emission

Summary form only given. The energy levels from which electric dipole radiation is forbidden are called metastable. An atom or molecule in metastable state can have much longer life-time than typical excited species which decay via electric dipole radiation. Moreover, metastable levels are highly excited above the ground state so that metastable species can act as an energy reservoir. Because of these unusual properties, metastable species have been an interest in various fields such as geophysics, gas discharge lasers, and material processing plasmas. We study on Argon metastable and 4p state neutral atom density in magnetized ICP and/or Helicon plasmas by Laser Induced Fluorescence and plasma emission. The electron densities are measured by using a Langmuir probe and Laser Thomson scattering method. The results show that metastable density is too low at the center of chamber due to significant neutral depletion. Otherwise, 4p state is high at the center of chamber because electron density is very high.¹ Power and pressure dependence of metastable and 4p state neutral atom have been spatially measured in the radial direction of cylindrical chamber.