Experimental Study on Low-velocity-spread Axis-encircling Electron Gun

S. G. Jeon, C. W. Baik, D. H. Kim, B. Jia, G. S. Park, N. Sato, K. Yokoo

Research output: Contribution to journalConference articlepeer-review

Abstract

The axial velocity spread was measured using a pin-hole and phosphor screen and the result was compared with the theoretical estimation. The theoretical calculations had been performed by using a new single-cusp gun theory that considered the discrepancy of the electron beam line and the magnetic flux line in the area of the cathode and anode. The specific thing of the new theory is the possibility of a fairly low velocity spreads just by controlling the distance between the cathode and the magnetic cusp, under well optimized another parameters. In this experiment, to verify the validity the theory, a 30 kV, 1.0 A Pierce-type electron gun was used with a peak magnetic flux density of 4.38 kG. The magnetic field has an asymmetric magnetic cusp by which the electron beam can be made to be an axis-encircling electron beam. And the position of the cathode can be changed using a micrometer to control the distance between the cathode and the magnetic cusp. To measure the axial velocity spread, a small amount of the electron beam was sampled using a pin-hole and the image of it on the phosphor screen was analyzed to calculate the axial velocity spread. The velocity ratio of the electron beam denned as the transverse velocity over axial velocity was also measured using the capacitive probe. The velocity ratio should be obtained before calculating the axial velocity spread because it has to be used in the analysis of the electron beam image on the phosphor screen. The result of the measurement of the axial velocity spread followed closely the theoretically estimated values. The minimum value of the axial velocity spread was about 2%.

Original languageEnglish
Number of pages1
JournalIEEE International Conference on Plasma Science
Publication statusPublished - 2003 Oct 17
Event2003 IEEE International Conference on Plasma Science - Jeju, Korea, Republic of
Duration: 2003 Jun 22003 Jun 5

ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics
  • Condensed Matter Physics
  • Electrical and Electronic Engineering

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