D. Kehne

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.

Experimental studies of emittance growth in a nonuniform, mismatched, and misaligned space‐charge dominated beam in a solenoid channel

Experimental and numerical studies of emittance growth resulting from beam mismatch have been performed at the University of Maryland Electron Beam Transport Experiment. A 5‐beamlet distribution of energy 5 keV and total current 44 mA passes through two‐solenoid matching lenses and into a 36‐solenoid transport channel. Theory predicts substantial emittance growth due to density nonuniformity, beam mismatch, and beam misalignment. Experimentally, the 5‐beamlet configuration is mismatched and transported through the channel. Random misalignments in the channel produce a gradually growing offset in the beam. The final emittance is measured for the mismatched beam. Simulation results of the matched and mismatched beams reveal that a large halo accounts for the emittance growth in the mismatched case. This is supported by experiment. The difference between the experimental emittance data and the numerical simulation is analyzed and attributed to the fact that the density of the halo is below the detection thre...

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 electron beam transport in the maryland periodic solenoid channel

Abstract In the University of Maryland electron beam transport experiment, a 5 kV, 0.2 A electron beam from a thermionic electron source (cathode radius r c = 1.27 cm and cathode temperature kT = 0.12 eV) is injected into a periodic focusing channel consisting of 38 solenoid lenses with period length S = 13.6 cm. The magnetic focusing fields of the channel, and hence the phase advance without space charge, can be varied over a wide range. We report emittance measurements and results of the effects of beam mismatch, misalignments and nonlinear lens forces on beam transport and emittance growth.

Numerical and experimental studies of halo formation due to mismatch in a space-charge dominated electron beam

Numerical and experimental studies of emittance growth and halo formation arising from beam mismatch have been performed. A mismatched 5 keV, 44 mA electron beam distribution passes through a 36-solenoid transport channel. Past studies have verified the agreement between experiment, simulation, and theory. Past simulation results show that a halo is responsible for emittance growth that results from the mismatch. Now simulation is used to find correlation between the initial distribution and the halo.<<ETX>>

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.

Experimental studies of emittance growth due to initial mismatch of a space charge dominated beam in a solenoidal focusing channel

Experimental studies of emittance growth resulting from beam mismatch have been performed. A five-beamlet distribution of 44 mA and 5 kV passes through two solenoid matching lenses and into a 36-solenoid transport channel. Theory predicts substantial emittance growth due to mismatch. The five-beamlet configuration is mismatched, and the final emittance is measured. Experiment and simulation results suggest that a large halo is the source of the predicted emittance growth.<<ETX>>

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.

Maryland Transport Experiment comparison to theory and simulation

The Maryland Transport Experiment employs a beam of low energy electrons to study, on a scaled basis, the nonlinear physics of space‐charge‐dominated transport which is important to a range of accelerator systems. Several series of experiments are discussed, which have investigated significant aspects of both the transverse and longitudinal physics, along with the generally high level of agreement which has been attained in comparisons to theory and simulation.