SPACE AND COSMIC RAY PHYSICS SEMINAR

University of Maryland
Atlantic Building, Room 2400
4:30 PM Monday, November 21, 2005
Coffee, Tea & Snacks 4:15-4:30 PM

Peter H. Yoon
University of Maryland

Self-consistent generation of suprathermal electrons (kappa distribution) by beam-plasma interaction

It was known since the early days of plasma physics research that suprathermal electrons are generated during beam-plasma laboratory experiments. Suprathermal electrons (the κ distribution) are also ubiquitously observed in space. To explain such a feature, various particle acceleration mechanisms have been proposed. However, self-consistent acceleration of electrons in the context of plasma kinetic theory has not been demonstrated to this date. This talk reports such a demonstration. It is shown that the collisionality, defined via the so-called "plasma parameter" plays a pivotal role. It is found that small but moderately finite value of g is necessary for the suprathermal tail to be generated, implying that purely collisionless Vlasov theory cannot produce superthermal population.