Reduction of Enhanced Edge Emission in a Large Area Electron Beam
Abstract
This paper presents measurements of the enhanced current density along the edges of a large area electron beam as well as successful techniques that eliminate this edge effect/beam halo. The spatial and temporal current density data is obtained with a Faraday cup array at the anode, and the spatial, time-integrated current density is obtained with radiachromic film. MAGIC particle-in-cell (PIC) simulations support the experimental results. Experiments and simulations show that recessing the cathode reduces the electric field at the edge and eliminates the edge effect. However the field shaper itself emits under long-term repetitive operation. In contrast using a floating metallic electric field shaper, which is electrically insulated from the cathode, eliminates the beam halo and prevents or minimizes electron emission from its surface during repetitive operation.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jan 01, 2002
- Accession Number
- ADA480409
Entities
People
- Frank Hegeler
- John D. Sethian
- M. C. Myers
- Michael A. Friedman
- Stephen B. Swanekamp
Organizations
- United States Naval Research Laboratory