Density measurement of plasma by CO2 Laser Interferometer

Abstract

A method of using CO₂ laser interferometer is described for the density measurement of intermediate region (the product of denstity n and plasma diameter d is around 10¹⁵ cm^-2). Michelson type interferometer is adopted and one-tenth of fringe corresponds n x d≅1.05 x 10¹⁵ cm^-2. Ge-Cu photoconductor cooled by liquid helium is used as a dector with fast time reponse. These are applied for the density measurement of plasma of BSG device⁸⁾⁹⁾ and it is confirmed that this method is reliable and easy technique for the purpose.