  Extra Ordinary (X) mode conversion to Bernstein wave near Upper Hybrid
Resonance (UHR) layer plays an important role in plasma heating through
cyclotron resonance. Wave generation at UHR and parametric decay at high power
has been observed during Electron Cyclotron Resonance (ECR) heating experiments
in toroidal magnetic fusion devices. A small linear system with ECR and UHR
layer within the system has been used to conduct experiments on X-B conversion
and parametric decay process as a function of system parameters. Direct probing
{\em in situ} is conducted and plasma heating is evidenced by soft x-ray
emission measurement. Experiments are performed with hydrogen plasma produced
with 160-800 W microwave power at 2.45 GHz of operating frequency at $10^{-3}$
mbar pressure. The axial magnetic field required for ECR is such that the
resonant surface (B = 875 G) is situated at the geometrical axis of the plasma
system. Experimental results will be presented in the paper.

Plasma Physics