Improvement in the Flat Probe Diagnostics for Arbitrary Degree of Anisotropy

We investigate operation of the flat probe for measurements of the anisotropic ion or electron velocity distribution function (IVDF or EVDF). Particular attention was given for the limiting case of very narrow VDFs. A new algorithm for analysis of the flat probe data was developed. Method was verified for EVDF in low pressure, low voltage beam discharge. Big departure from previous traditional method was demonstrated. Experimental measurements of EVDF were performed 1, 2 and compared with Monte Carlo simulations. Good agreement between two was observed.