Two color fiber optic interferometer for gas and plasma density measurements

Summary form only given. A 2-color, 4-beam Fiber Optic Interferometer (FOI) with /spl sim/10/sup -4/ wave sensitivity when sampled at 1 /spl mu/s intervals is being built to measure gas and plasma densities. The final instrument will be completed under a 2 year SBIR contract; initial results from one beam of the instrument will be presented. The FOI uses 1310 nm and 1550 nm CW diode lasers and is contained in a /spl sim/6"/spl times/17"/spl times/17" volume, which makes the system compact and portable. The two colors enable the FOI to measure neutral gas and plasma densities simultaneously (Weber and Fulghum, 1997), so that partially ionized plasmas can be characterized. The multiple beams in the complete instrument will allow rapid characterization of gases and plasmas, including the measurement of correlated density variations. Neutral gas and electron density profile measurements have been taken as a function of time from a supersonic nozzle designed for z-pinch loads and a cable gun.