The energy deposition efficiency and focal spot dynamics of electron beams produced by pulsed cold-cathode highvoltage glow discharges for metal surface treatment are investigated for two different cathode geometries. A concave cathode geometry in which the focusing is dominated by the convergence of the electric field lines in the cathode fall region is compared with a flat cathode in which th...

Title of Thesis: FABRICATION AND MEASUREMENT OF CESIATED METAL PHOTOCATHODES Nathan A. Moody, Master of Science, 2004 Thesis Directed By: Professor Patrick O’Shea Department of Electrical and Computer Engineering A requirement for accelerator applications such as free electron lasers is a high current, high quality electron beam. This is achieved using a photoinjector, where a drive laser modul...

Most vacuum devices are hampered by ion bombardment due to residual gases. Sometimes, it causes the breakdown of devices and shortens their life. In this article, the effect of the ion bombardment on the cathode surface in a structure of a field emission display was simulated. In this structure, a special type of spacer was used, named “hop” and “flu” spacer. The trajectories of electrons emitt...

The thermally assisted photoemission (TAPE) effect was investigated for the hexaboride thermionic cathodes (LaB6 and CeB6). It was found that the quantum efficiency of these cathodes can be increased by raising the cathode temperature along with the thermionic emission. In addition both materials can emit a measurable photoemission current by being irradiated with a laser having a photon energy...

The results of a study the long-term reproducibility emission characteristics electron sources with field density up to 1000 A/cm 2 based on composite nanocarbon films are presented. It was found that high-current is accompanied by sputtering residual gas ions from atoms cathode material and its sedimentation anode. can be used predict durability diamond-graphite cathodes when operating in unst...

The Magnetron is one of the efficiency high-power microwave source, although the energy conversion efficiency decreases with pulsed-power relativistic electron beam. We study the capability to increase energy conversion efficiency of Relativistic Magnetron by using Transparent Cathode. The Transparent-Cathode consists of independent cathode strips. Each cathode strip caused azimuthal magnetic f...

We report on experimental and theoretical investigations of a 17 GHz RF photocathode electron gun. This is the first photocathode electron gun to operate at a frequency above 2.856 GHz. The 1.5 cell, π−mode, copper cavity was tested with 50 ns pulses from a 17.150 GHz klystron amplifier built by Haimson Research Corp. A Bragg filter was used at the RF gun to reduce the reflection of parasitic m...

An experimental investigation of the operating characteristics of 3.2 mm diameter orificed hollow cathodes was conducted to examine low-current and low flow rate operation. Cathode power was minimized with low orifice aspect ratio and the use of an enclosed keeper. Cathode flow rate requirements were proportional to orifice diameter and the inverse of the orifice length. Cathode temperature pro...

Field emitters can be used as a cathode electrode in a cathodoluminescence device, and single-walled carbon nanotubes (SWCNTs) that are synthesized by arc discharge are expected to exhibit good field emission (FE) properties. However, a cathodoluminescence device that uses field emitters radiates rays whose intensity considerably fluctuates at a low frequency, and the radiant fluctuation is cau...

Wide band gap materials show promise for applications in coating of field emission tips. Recently nanocrystalline hexagonal GaN crystallites as small as 5 nm average diameter have been formed using reactive laser ablation of gallium metal in a nitrogenating ambient. In this paper we have investigated the performance of ungated emitter. Silicon tip arrays coated by dielectrophoresis of gallium n...