D Bora
Articles written in Pramana – Journal of Physics
Volume 14 Issue 3 March 1980 pp 175-183 Plasma Physics
Electron and plasma stream reflection at a nonadiabatic mirror
Experimental investigations of the phenomena occurring when low density electron and plasma beams are injected into a nonadiabatic magnetic mirror are presented. Effects of nonadiabaticity and mirror ratio on the reflectivity of the magnetic mirror are measured. Transition of the mirror from adiabatic to strongly nonadiabatic results in setting up of a potential barrier which enhances the reflectivity.
Volume 27 Issue 4 October 1986 pp 549-561 Plasma Physics
Effect of radio frequency field on toroidal plasma parameters
D Bora K Satyanarayana V N Rai
Low temperature plasma parameters in a toroidal magnetic field are measured. The effect of an externally applied perpendicular electric field on the plasma parameters is studied. The lifetime of the plasma is measured in the presence and absence of the RF electric field. Decrease in the plasma lifetime in the presence of RF field is attributed to detrapping of the primary electrons to a larger volume. Plasma lifetime increases when a small vertical magnetic field is added to the toroidal magnetic field.
Volume 56 Issue 4 April 2001 pp 551-557 Research Articles
RF breakdown by toroidal helicons
Bounded whistlers are well-known for their efficient plasma production capabilities in thin cylindrical tubes. In this paper we shall present their radio frequency (RF) breakdown and discharge sustaining capabilities in toroidal systems. Pulsed RF power in the electronmagnetohydrodynamic (EMHD) frequency regime is fed to the neutral background medium. After the breakdown stage, discharge is sustained by toroidal bounded whistlers. In these pulsed experiments the behaviour of the time evolution of the discharge could be studied in four distinct phases of RF breakdown, steady state attainment, decay and afterglow. In the steady state average electron density of ≈1012 per cc and average electron temperature of ≈20 eV are obtained at 10−3 mbar of argon filling pressure. Experimental results on toroidal mode structure, background effects and time evolution of the electron distribution function will be presented and their implications in understanding the breakdown mechanism are discussed.
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