Role of extraordinary waves in uniform electron cyclotron resonance plasmas

The extraordinary wave (X wave) was found to contribute to the uniformity of an electron cyclotron resonance (ECR) plasma whose electron density is about 1–2×1017 m−3. The X wave propagated radially in the plasma both before and after the ECR point. The electron density jump occurred when the electron density was equal to the cutoff density of the X wave at the ECR point. Upon increasing the electron density, only the whistler wave propagated in a high density plasma of about 1018 m−3.