Response of Energetic-Particle-Driven Magnetohydrodynamics (MHD) Instability to Modulated ECH in Heliotron J

The response of energetic particle (EP)-driven magnetohydrodynamic instability to electron cyclotron heating (ECH) was experimentally studied in Heliotron J. The neutral beam injection power remained constant throughout the experiment, and the ECH power was systematically modulated. When the ECH power was gradually decreased to a certain threshold, the excitation of an EP mode with a frequency of approximately 100 kHz was observed. The response to ECH showed a close linkage with variations in electron density and temperature. In addition, a distinct delay response effect concerning plasma pressure suggests a complex delay response of mode excitation and suppression.