Enhanced Channel Tracking Due to Beam-Generated Magnetic Fields,
Abstract
The complete frozen-field Maxwell equations are used to study the tracking behavior of an electron beam in a channel. The three type of channels considered contain conductivity, reduced density or a combination of both. The analytic work includes the derivation of the tracking force for a beam propagating entirely inside a square conductivity channel. The resulting expression reduces to E. Lee's electrostatic expression in the limit of small conductivity. However, for finite conductivity, magnetic tracking is dominant near the head of the beam, particularly for short rise-time beams. The numerical work using the three-dimensional simulation code IPROP shows high values for channel tracking with large optimal initial conductivities (roughly 1 * 10 to the 10th power scaler conductivity).For all three types of channels, tracking forces of > or = 20 gauss are calculated for fast-rise 10-kA pencil beams in a 1-cm channel. Trumpet-shaped beams require larger channel radii to produce significant tracking. Forces of approximately 5 gauss are calculated for a 5-cm offset channel with 3-cm radius. This work suggests tracking forces may be an order of magnitude greater than previously thought.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jun 10, 1986
- Accession Number
- ADA190899
Entities
People
- B. B. Godfrey
- Danny R. Welch