Effects of magnetic field and target plasma on the penetration behaviour of compact toroid plasma by heat load measurements in CPD

Abstract

Compact toroid (CT) injection experiments have recently been carried out in a compact plasma wall interaction experimental device (CPD) in the presence of toroidal as well as poloidal magnetic field and low density RF target plasma. Spectroscopic studies have been carried out using an IR camera, an IR spectrometer and an Hα monitor to estimate the heat load deposition on the target and also to study the magnetic field as well as RF target plasma effects on CT plasma penetration behaviour. Using IR camera imaging of the target plate, heat load deposition on it has been estimated from the observed temperature rise of the plate and has been compared with the energy content of CT plasma. The estimation suggests that nearly 700 J of energy is uniformly deposited on the target plate under vacuum condition without any magnetic field. On the other hand, post exposure analysis of target plate using scanning electron microscopy has indicated local melting of the target plate. It has been observed that radial penetration of CT towards the target plate is reduced with the increase in the external magnetic field, both toroidal and poloidal. Moreover, the presence of RF target plasma in external magnetic fields seems to change the CT penetration behaviour significantly.