Ion Loss by Collisional Upscattering
Abstract
In at least one idealized version of the Polywell (tm)/SCIF (spherically Convergent Ion Focus) fusion scheme, the ions are injected at a point xo such that the magnetic field is sufficiently reduced from its maximum value that the ion orbits are nearly straight lines as they converge to the center of the device. Typically, this location will have a B-field in the range of 100 Gauss, compared to a B max of several kG. This convergence in a strong potential produces a highly non-Maxwellian ion distribution, with a small dense core of nearly monoenergetic ions surrounded by a large mantle of less dense plasma made up of ions whose velocity is primarily radial. There are two very distinct effects that collisions have on ion confinement. Firstly, as the ions pass through the geometric center of the device, collisional processes will alter their velocity distribution from nearly monoenergetic to Maxwellian. Secondly, as the ions traverse the mantle of lower density plasma outside the core, collisions can transfer momentum from primarily radial flow, which produces good spherical convergence, to a more isotropic distribution of velocities.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jan 20, 1991
- Accession Number
- ADA257688
Entities
People
- Marlene Rosenberg
- Nicholas A. Krall