Showing papers by "Marshall N. Rosenbluth published in 1980"

Filamentation of a heavy‐ion beam in a reactor vessel

Abstract: A heavy‐ion beam driver for inertial confinement fusion is subject to filamentation instability over a broad range of beam and plasma background conditions. The case of a beam injected into a gas‐filled reactor vessel, where finite pulse length and propagation distance play an important role in limiting mode growth, is analyzed. The effects of transverse thermal spread, spherical convergence to the pellet, and finite magnetic decay rate of eddy currents are included in this treatment. It is concluded that a cold beam will be severly disrupted unless the product of magnetic plasma frequency and propagation time is not large compared with unity. If this condition is not met, mode growth may still be limited to about six e folds by adding transverse velocity spread such that the pulse tail is in a state of pinch equilibrium. However, this approach causes much of the pulse to be lost by thermal expansion.

Axis encircling ion gyroinstability

Abstract: An idealized plasma model in which all the ion guiding centers lie along the magnetic axis of a cylindrically symmetric plasma is investigated. The radial eigenvalue equation is derived and solved for this strongly unstable limit. Many of the physical features predicted by simple analytic limits of the WKB phase integral condition are verified by a comparison with the results of a particle simulation.

Reply to the comments by K. Itoh and S. Inoue

Abstract: The assertion by Itoh et al. of the stability of the collisional shear Alfven wave, based on a quadratic form derived by them, is accepted. The difficulties involved are claimed to result, not from an incorrect expansion, but from difficulties in matching of inner and outer solutions. (AIP)