D. X. Wang

Beam emittance measurement by the pepper-pot method☆

Abstract A simple formula is derived to calculate the beam emittance from a pepper-pot measurement. An example illustrating how to apply this method is given.

Performance characteristics of a variable-perveance gridded electron gun

A variable-perveance gridded electron gun has been designed, constructed, and extensively tested. The gun can produce a 2.5-kV, 40-mA, 50-ns fast electron beam pulse with good beam-optical properties. The gun has extremely flexible design features and can be operated in a wide range of parameters with the maximum beam energy up to 10 kV and beam current of hundreds of milliamperes. The perveance of the gun can be changed by adjusting the A-K gap and the grid-cathode voltage to maintain the optimum beam-optical properties. >

Electron beam injector for longitudinal beam physics experiments

Design parameters of the electron beam injector for longitudinal compression and resistive wall instability experiments are discussed. The performance characteristics of its components and the injector system are presented.<<ETX>>

Experimental verification of a longitudinal beam-envelope model for a space-charge dominated parabolic bunch

The longitudinal drift expansion and compression of a space‐charge dominated electron beam with a parabolic line charge profile has been studied experimentally to verify the validity of the longitudinal envelope equation. The experimental configuration and measurement results are reported. Good agreement is found between theoretical predictions from the envelope calculations and experimental results.

Longitudinal expansion of space‐charge dominated drifting beam bunches with a parabolic line charge density distribution

An experiment was performed for the first time to demonstrate linear longitudinal space‐charge forces on drifting electron beam bunches with a parabolic line charge density distribution. The parabolic electron beam bunch was produced by a gridded electron gun and guided into a short transport channel consisting of an induction acceleration module and three matching lenses. The time‐resolved beam energy was measured at the end of the channel by both a retarding field energy analyzer and a deflecting field energy analyzer. The experimental results were compared with theory and good agreement was found.

Design and performance characteristics of a compact induction acceleration module for longitudinal pulse compression experiments

Abstract A compact induction acceleration module has been designed and constructed for electron beam experiments at the University of Maryland aimed at investigating the physics of longitudinal bunching and compression. The module imparts a front-to-tail energy shear to the pulsed electron beam (15–50 ns) causing longitudinal compression in a 5 m long periodic solenoid channel. The design parameters, operating principle and performance characteristics of this device are reported in this paper.

Experimental studies of longitudinal dynamics of space-charge dominated electron beams

A comprehensive experimental program was carried out at the University of Maryland Beam Transport facility to study the longitudinal beam physics of space-charge dominated bunches. This investigation included the behavior of (a) bunches with parabolic line charge profile, (b) bunches with rectangular line charge profile, and (c) local perturbations (slow and fast waves) in rectangular bunches. The major experimental results are presented in this paper.

Longitudinal expansion and compression of electron bunches with rectangular line charge profiles

SummaryThe longitudinal expansion and compression of a space-charge-dominated rectangular electron bunch have been investigated at the University of Maryland Electron Beam Transport Facility. In this paper we report the experimental results and comparison with theoretical prediction and 1D PIC simulations.

Longitudinal kinetic energy spread from focusing in charged particle beams

A charged particle beam can be given a longitudinal kinetic energy spread through focusing by magnetic solenoid lenses. Measurements of energy spread are reported and are compared with the results of computer simulations, which include several known sources of energy spread. These sources are discussed. The results of the measurements and the simulations agree, giving energy spreads which are two orders of magnitude larger than the initial thermal energy spread.<<ETX>>

Studies of space-charge waves due to localized perturbations in an electron beam

SummarySpace-charge waves in the form of localized perturbations to the initial beam velocity, density and current, are generated in a space-charge-dominated electron beam. Their propagation on the beam has been measured. The experimental results are presented in this paper.