Two dimensional lithium beam imaging technique has been applied in the spherical tokamak, CPD (Compact Plasma wall interaction experimental Device), to study the effects of various magnetic field configurations on RF plasma confinement topology. The performance of the lithium sheet beam is absolutely calibrated by a quartz crystal monitor. Experimental results show that plasma initiation takes place at the electron cyclotron resonance layer in a simple torus configuration and then it expands quickly to the lowmagnetic field side. Different magnetic field configurations critically affect the RF plasma confinement topology. A sharp lower boundary exists for the RF plasma in magnetic null configuration. Magnetic connection length plays the key role in defining plasma boundary and the critical value of connection length for plasma to exist in CPD is found to be ~ 5-6 meter for a given pressure condition.
All Science Journal Classification (ASJC) codes
- Condensed Matter Physics