Plasma density measurement using a simple microwave technique

Abstract

We describe a simple method of determining the plasma density unambiguously with the help of a microwave interferometer. The frequency of the Klystron source is modulated with the help of a staircase voltage pulse. The height of each staircase is adjusted in such a way that the corresponding phase shift is 90°. Signals proportional to the cosine and sine of the phase shift due to plasma are generated, and the plasma density is unambiguously measured. The advantages of the method are highlighted in the text.