Accession Number:

ADA220466

Title:

Experimental Determination of the Electric Field and Charge Distribution in Magnetically Insulated Ion Diodes

Descriptive Note:

Corporate Author:

CORNELL UNIV ITHACA NY LAB OF PLASMA STUDIES

Report Date:

1987-03-01

Pagination or Media Count:

53.0

Abstract:

The electric field distribution is measured across the high voltage gap of a magnetically insulated intense ion beam diode by observing the Stark shift of line-emission from ions accelerating in the gap. The measured distribution yielded the time dependence of the actual diode gap. Rapid gap closure was observed early in the pulse, resulting from expansion of the electric field-excluding electrode plasmas in the diode. This can contribute substantially to the previously observed ion current density enhancements over the values calculated based upon the mechanical diode gap. Assuming planar geometry the electric field distribution was used to determine the electron density across the diode gap. This was compared with one-dimensional Brillouin- flow model calculations using the actual acceleration gap. The electrons were observed to spread towards the anode beyond the region of the theoretical electron-sheath. The electron presence near the anode was further enhanced when a cathode vane was used. In addition, an increase in the total electron number in the gap relative to analytic theory was inferred. This serves to explain the enhancement of the measured ion current density over the one calculated using the actual diode gap that we observed for the configuration tested. JHD

Subject Categories:

  • Electricity and Magnetism

Distribution Statement:

APPROVED FOR PUBLIC RELEASE