Gradient Driven Instability in Multi-pole Line Cusp Magnetic Field Plasma Device (MPD)

The Multi-pole Line Cusp Magnetic Field Plasma Device (MPD) is designed to study plasma behavior under flexible magnetic confinement. It creates a low-field, stable region in the center of the chamber, ideal for study the unmagnetized plasma confined by multipole line cusp magnetic field. A key feature of this setup is that the magnetic field’s curvature center lies outside the plasma volume, which helps suppress instabilities and allows the confinement of high-beta plasma, where plasma pressure is comparable to magnetic pressure. Gradients in the system can be varied by changing the pole cusp magnetic field.

Recent experiments have explored the behavior of localized magnetic cusp fields generated by selectively powering only two electromagnets at a time. This configuration facilitates the excitation of coherent modes with frequencies expected within the ion cyclotron frequency range. The ongoing study aims to understand the influence of hot electron populations on mode dynamics. By systematically varying the magnetic field strength at the poles, the experiment seeks to characterize instabilities driven by plasma parameter gradients. These findings will helpful to produce quiescent plasma.