Electron Acceleration due to Electric Field Bursts close to the Lower
Hybrid Frequency in a High-Voltage Linear Plasma Discharge

Y. Takeda, H. Inuzuka 1)


Department of Physics, College of Science and Technology
Nihon University, Kanda Surugadai 1-8, Tokyo 101-8308, Japan

1) Department of Electrical and Electronic Engineering, Faculty of Engineering, Shizuoka University, Johoku 3-5-1, Hamamatsu 432-8561, Japan

This paper presents our new findings that strong electric-field bursts, which were generated in a high-voltage linear plasma discharge, give rise to electron acceleration evidenced by impulsive hard X-ray fluxes with energies higher than 20 keV detected from the direction perpendicular to the magnetic field and also from the direction almost parallel to the magnetic field.
Dependence of the angular distribution of hard X-ray fluxes on the spectral profile of an originating electric-field burst is explained according to the theory of transit time interaction of a lower hybrid wave. The recent theory of nonadiabatic electron acceleration by a large amplitude low frequency wave such as a lower hybrid wave is also invoked to explain the dominant electron acceleration in the direction perpendicular to the magnetic field.
Moreover, contribution of laminar electric field pulses such as double layers and localized potential structures to the acceleration of high energy electrons is compared with that of a fairly coherent lower hybrid wave packet. The lower hybrid wave packet is exceedingly efficient to accelerate high-energy electrons.