PULSE HEATING OF MATERIALS BY HIGHLY CONCENTRATED ELECTRON BEAMS.
Abstract
An existing high perveance electron gun with a high area convergence ratio was adapted for the experiments. A cathode diam. of 0.6 cm or an area of 0.5 sq. cm was chosen. This resulted in a specific cathode load of 5 amperes/sq cm at 10,000 volts. Such a current was drawn from a pure Ta surface heated to 2600 K by electron bombardment. The electron energy was uniformly absorbed in a layer of material with a thickness corresponding to 2.6 x 10 to the -4th power g/sq cm. At the beginning of the pulse, the exposed area of this layer corresponded to the vacuum electron beam cross-section, but was reduced very rapidly by additional ion focusing caused by material evaporation. Experiments were performed using a condensor discharged through the gun for bombarding solid Ta as well as thin Ta foils. Craters and surface explosions on the targets were observed. Thin foils were punctured by the beam producing a liquid film. A jet of evaporating Ta then accelerated, by its recoil force, the film in the direction of the beam. The film was torn apart forming a series of small droplets. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Jan 01, 1962
- Accession Number
- AD0275265
Entities
People
- Oskar Heil
- Siegfried Vogel
Organizations
- Air Force Cambridge Research Laboratories