Injection, Propagation, and Magnetization of Plasma Beams in a Transverse Magnetic Field and a Magnetized Plasma.

Beam propagation experiments were performed with various plasma sources to understand the physics of plasma motion in a transverse magnetic field and magnetic diffusion in a plasma. These experiments could clarify different features of the beam transport process in a magnetic field, depending on dimensionless parameters such as: plasma dielectric constant (varepsilon), plasma beta (beta), normalized beam-width ( Deltay/rho_{rm i}). The high-energy H^{+} beams (neutralized ion beams) were produced by a flashover, magnetically insulated ion diode, with parameters: (ion energy, drift velocity, density, temperature, and magnetic field) = (120 ~ 350 keV, 4.8 ~ 7.0 m/mus, 4.4 times 10^{10 } ~ 1.2 times 10^{11} cm ^{-3}, T_{ rm e} ~ 50, 100 eV, respectively and B_{rm z } <=q 400 G). These beams are categorized as a high-beta (beta > 1), and large-gyroradius beam (Deltay/rho_ {rm i} < 1). The high-beta beam was observed to propagate by the ExB drift at the initial velocity, as found previously for the low-beta beam in the large -gyroradius limit. The magnetization time in the large -gyroradius limit was four orders of magnitude faster than predicted from classical Spitzer conductivity. When the beam was injected into a magnetized plasma, the induced E field was shorted out, and the neutralized ion beam was deflected due to the Lorentz force. The low-energy H^{+} bean was generated by a deflagration-mode plasma gun, with parameters: (50 eV, 6 cm/mus, 4.5 times 10^{12 } cm^{-3}, T_{rm i} ~ 1 eV, T_{rm e} ~ 5 eV, and B _{rm z} <=q 300G). The gun-plasma beam is classified as high -to-low beta (0.1 < beta < 10), small-gyroradius (Delta y/rho_{rm i} > 1) and a long-range propagating limit (L/rho_{rm i} gg 1). In these limits, a brief initial state of diamagnetic propagation was observed for beta >=q 1, followed by ExB propagation for beta < 1, accompanied by beam deceleration, transverse compression, and thermalization of the beam energy. A wide range of diamagnetism was observed, depending upon plasma-beta, unlike the large -gyroradius limit. Both experiments suggest that the normalized beam -width (Deltay/rho_ {rm i}) is an important parameter which determines the magnetic diffusion time-scale, as is the plasma-beta. Faster magnetization was apparent for the large-gyroradius beam than for the small-gyroradius beam. Overall, the observed magnetic diffusion time is more of the order of the diffusion time based on Hall conductivity with classical diffusion rather than Spitzer, Pedersen conductivity, or conductivity based on turbulence.