Collisional Equilibration
Abstract
It is of interest to estimate spreading of initially-radially- monoenergetic energy distributions and of the ion spatial convergence radius due to ion/ion self-collisions in the core. Lovberg has shown that these effects can be kept non-dominant in system operation. The first complete analysis of collisional equilibration of particles with initial uniform and equal energy was carried out by Maxwell in 1859, who showed that the stable state distribution of energy (or velocity) was (what we now call) the Maxwell (or Maxwell-Boltzmann) distribution. In the central core, ion/ion collisions will produce this distribution, albeit with a truncated tail (for some conditions, as explained above) with the consequences described previously. This distribution is achieved by the combined effect of a very large number of small-angle collisions of each particle with the Coulomb fields of the surrounding particles that can affect its motion. These are limited to those contained within a sphere around each particle with radius equal to the Debye shielding radius. For ion core energies E(c)> 1E3 eV, the Debye sphere will contain a very large number of ions for any density n < 1E19/cu cum(3), thus most collisions-deflections will be due to distant small-angle encounters. Any one collision will yield only a small deflection and momentum transfer to the deflected particle.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jan 01, 1991
- Accession Number
- ADA257686
Entities
People
- Robert W. Bussard