A technique of laser pulse shaping was developed for low-emittance electron beam generation in a photocathode RF gun. The emittance growth due to space charge and RF effects in the RF gun was experimentally investigated with square and gaussian temporal laser pulse shapes. It is found that the square pulse shaping is a useful tool for both the reduction of nonlinear space charge force and the c...

An electron gun with large compression of a thin annular beam for generation of high-power microwaves and IR radiation has been designed. Computer simulations of beam formation in the gun show some hysteresis effects: a beam with different current can exist in the same external conditions. At the upper (metastable) part of a hysteresis curve the beam current exceeds Child-Langmuir current. Expe...

A "multiple beamlet" experiment aimed at investigating the transverse space charge effect was recently conducted at the Argonne Wakefield Accelerator. The experiment generated a symmetric pattern of 5 beamlets on the photocathode of the RF gun with the drive laser. We explored the evolution of the thereby produced 5 MeV, space-charge dominated electron beamlets in the 2m drift following the RF ...

An ultra-high vacuum loadlock system capable of operating at high voltage has been added to Lhe SLC Polarized Electron Gun. The unit incorporates facilities for heat cleaning, activating and measuring the quantum efficiency of photocathodes. A tray of up to four photocathodes can be exchanged without bringing the activation unit or gun up to atmosphere. Low voltage quantum efficiencies of 20% h...

This article is a survey of hardware and software advances that promise to increase the power and sensitivity of electron energy-loss spectroscopy (EELS) and energy-filtered imaging (EFTEM) in a transmission electron microscope. Recent developments include electron-gun monochromators, lens-aberration correctors, and software for spectral sharpening, spectral processing and interpretation of fin...

The performance tests were done for a 1.6 cell s-band BNL-type photocathode RF electron gun, GUN-IV, under a condition of 1.5MW RF power input and 266nm Nd:YAG laser pulse irradiation. As a result, the maximum energy and the maximum charge/ bunch were obtained as 1.6 MeV and 120 pC/bunch, respectively. In addition, a sinusoidal behavior of current with the polarization angle of laser light were...

New type of high perveance electron guns with convex cathode has been developed. Three guns described in this article are built to provide transverse electron current density distributions needed for Electron Lenses for beam-beam compensation in the Tevatron collider. The current distribution can be controlled either by the gun geometry or by voltage on a special control electrode located near ...

We report on the electron analog of the single-photon gun. On-demand single-electron injection in a quantum conductor was obtained using a quantum dot connected to the conductor via a tunnel barrier. Electron emission was triggered by the application of a potential step that compensated for the dot-charging energy. Depending on the barrier transparency, the quantum emission time ranged from 0.1...

When the outer electron of an alkali atom in an electric field is laser excited just above the field-induced ionization threshold, the electron ejection will not be instantaneous. Calculations show there are a number of energy regions where, upon short-pulse laser excitation, the atom will eject a train of electron probability pulses with the pulses being nearly equally spaced in time. This sys...