Strongly Eccentric Rotational Plasma Lamina Observed in a 2.45-GHz Hydrogen Discharge

A novel strongly eccentric rotating plasma lamina structure subtending approximately an angle of 120° is reported in a 2.45-GHz driven electron cyclotron resonance hydrogen discharge in the proximity of the chamber wall. Shape and rotation frequencies depend critically on the embedded magnetic field distribution in the plasma chamber as well as on neutral gas pressure and microwave power. The discharge denominated test-bench for ion-sources plasma studies includes a transparent doubled shielded quartz window that keeps the microwave resonance condition. An ultrafast microchannel plate charge-coupled device frame camera is used to obtain four pictures of 1-
$\mu \text{s}$
exposure time each during a single plasma pulse in the visible emission range.
$ {E} \times {B}$
drift is pointed as that responsible for driving the rotational behavior of a thick plasma sheath, where the scale of the quasi-neutrality breaking is estimated ten times greater than that in a typical plasma sheath.