Electron Emission Coefficient Research Articles

SGEMP Response Investigations with Exploding-Wire Photons

The exploding-wire photon experiments produced space-charge-limited boundary layers of thickness as small as a few centimeters. Comparison between the experimental results and state-of-the-art SGEMP calculations revealed the following features. Peak electric fields, surface currents and currents coupled into simple geometries were calculated within a factor of 1.5, with no normalization other than photoemission diode measurements of the electron current and average energy. Absolute agreement at low fluxes indicate that the electron-emission coefficients are measured by the diodes to an accuracy of better than 30%. The larger scatter in data at high fluxes on the disk experiment may be due to a combination of photon spectrum and rise time variations (especially in a soft component) between pulses and could possibly be affected by differences in minor contaminants on the test object and diode surfaces. The ratio of currents on the back and front of the disk is calculated to be a factor of 1.5 greater than measured. This discrepancy cannot depend on electron emission, and may indicate a need for finer gridding in calculating the edge of a disk. The leakage of electrons into a shadowed aperture is calculated within a factor of 1.4, but appears to persist somewhat longer than the calculations indicate.

The relation between the coefficient of secondary electron emission and the direction of spontaneous polarization of lithium niobate. (USSR)

The relation between the coefficient of secondary electron emission and the direction of spontaneous polarization of lithium niobate. (USSR)

Contributions to the study of secondary electron emission at the discharge tube wall

The dependence of the discharge current on both the secondary electron emission at the discharge tube wall and the tube diameter was studied. Results of the study are the following: (1) a decrease of the discharge current with the decrease of the coefficient of secondary electron emission; (2) the secondary electron emission occurs with a high intensity at the tube wall limiting the first dark space and with a lower intensity on the tube wall limiting the negative glow end; (3) the discharge current depends on the diameter of the discharge tube through the elementary processes occurring in the region of the cathode fall.

Proton−induced electron emission from characterized niobium surfaces

Both the electron emission coefficient (electrons/ion) and the energy distribution of emitted electrons have been determined for bombardment of polycrystalline niobium by 30−400 keV protons. In situ characterization of the niobium surfaces was accomplished using electron−induced Auger electron spectroscopy. Emission coefficient measurements were made for protons incident along the surface normal and along the axis at 45° from the surface normal. Electron energy distributions were determined using a hemispherical retarding analyzer with the proton beam at 45° from the surface normal and at 90° from and coplanar with the axis of the analyzer. The results are discussed and interpreted with reference to electron emission theories and previous experiments.

Some properties of pyrolitic boron nitride

Pyrolitic boron nitride is a pore-free, vacuum tight material possessing low dielectric permeability, moderate dielectric loss, and a very low (the lowest of all known materials) coefficient of secondary electron emission. Owing to this, pyrolitic boron nitride is a promising material for use in electronics technology. The high thermal conductivity, and especially the structure, determine the excellent resistance to thermal shock of the articles made from pyrolitic boron nitride. The relatively high density, the excellent resistance to oxidation, the chemical inertness to most reagents, the structural features, and especially the strength at elevated temperatures opens up wide possibilities for employing pyrolitic boron nitride in chemical and metallurgical industries, in semiconductor techniques, and other regions of technology.

A simple comparison method for determining the coefficient of secondary electron emission by positive ions

From the ratio of the collector currents of two ion gauges operating under identical conditions, the coefficient of secondary electron emission by positive ions for one collector can be deduced if that for the other collector is known. Changes in the coefficient, owing to oxidation of one collector surface for example, can also be followed provided the reference surface remains unaffected. Some results relating to the oxidation of molybdenum are included using molybdenum oxide as the reference surface.