Performance characteristics of a variable-perveance gridded electron gun

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Studies of the dynamics of longitudinal space-charge waves in space-charge dominated beams propagating through a transport channel with a long solenoid are performed at the University of Maryland. In this paper, we report some experimental results on the energy modulations converted from density modulations. By changing the working conditions of the electron gun, pure initial density modulations are generated. Energy perturbation waveforms are measured with a high-resolution energy analyzer. The experimental results are compared with both the linear theory and the simulation results. Good agreements are achieved for the relationship between the energy and current perturbation strengths.

“…1. A thermionic gridded electron gun [8] is used as the source of the electron beams. A highresolution energy analyzer [9][10][11] is installed in the system.…”

Section: Long Solenoid Experiments Setupmentioning

confidence: 99%

Experimental observations of longitudinal space-charge waves in intense electron beams

Tian

Zou

Cui

et al. 2006

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“…Input impedance of the cathode is very important for electron gun performance. The triode electron gun consists of cathode, grid, and anode [15]. A basic electronic circuit of the triode electron gun is shown in Fig.…”

Section: Derivation Of Input Impedance Of the Electron Gunmentioning

confidence: 99%

Measurement of beam energy spread in a space-charge dominated electron beam

Cui

Zou

Reiser

et al. 2004

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Characterization of beam energy spread in a space-charge dominated beam is very important to understanding the physics of intense beams. It is believed that coupling between the transverse and longitudinal directions via Coulomb collisions will cause an increase of the beam longitudinal energy spread. At the University of Maryland, experiments have been carried out to study the energy evolution in such intense beams with a high-resolution retarding field energy analyzer. The temporal beam energy profile along the beam pulse has been characterized at the distance of 25 cm from the anode of a gridded thermionic electron gun. The mean energy of the pulsed beams including the head and tail is reported here. The measured rms energy spread is in good agreement with the predictions of the intrabeam scattering theory. As an application of the beam energy measurement, the input impedance between the cathode and the grid due to beam loading can be calculated and the impedance number is found to be a constant in the operation region of the gun.

“…The apparatus consists of an electron gun [27], four short solenoids for matching, and a 1.5 m long solenoid. The system has been recently upgraded with additional diagnostics and improved noise shielding [28].…”

Section: A the Long Solenoid Experimentsmentioning

confidence: 99%

Experimental study of large-amplitude perturbations in space-charge dominated beams

Tian

Kishek

Haber

et al. 2010

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Detailed experimental measurements are presented concerning the propagation of space-charge waves of varying amplitudes in an intense, charged-particle beam. A short perturbation to the density profile is applied at the electron gun, and both current and mean energy profiles are measured at two locations downstream. The measurements are compared to predictions of a linear 1D cold-fluid model, and selfconsistent particle-in-cell simulations. For sufficiently small perturbation amplitudes, the experiment, simulation, and 1D theory agree. For larger amplitudes, the simulation begins to diverge from theoretical predictions due to nonlinear effects. Experimental observations for large-amplitude perturbations differ markedly from either theory or simulation. With the aid of simulations with mismatched and misaligned beams, this departure of experiments from predictions is demonstrated to be caused by the loss of beam current due to scraping aided by the larger radius of the perturbation.