Plasma refractive index measurements utilizing a He-Ne Vernier interferometric laser

The various laser output power waveforms which can be generated using a helium-neon vernier laser are described and their utilization in measuring plasma refractive indices is discussed. Utilizing the laser in the near degenerate configuration, a simple method is presented for determining the electron density of a CW plasma. Using the same configuration, fast current switching experiments are also described which are utilized to check this simple method and to obtain information about the gas density of the CW argon ion laser plasma investigated. Additional experiments utilizing the single-frequency configuration are discussed and its high sensitivity feature is compared with that of a conventional laser interferometer.