Beam experiments in the extreme space-charge limit on the University of Maryland Electron Ring

Abstract

Articles you may be interested in Relativistic solutions for one-and two-dimensional space-charge limited current in coaxial diode Phys. Plasmas 20, 053103 (2013); 10.1063/1.4804403 Amended conjecture on an upper bound to time-dependent space-charge limited current A fully kinetic model for the electron flow in a crossed field device is derived and used to determine the system stationary states. It is found that for low injection temperatures, there is a simultaneous presence of distinct stationary solutions and an abrupt transition between accelerating and space-charge limited regimes. On the other hand, for high injection temperatures, there is only a single stationary solution branch and the change between the regimes becomes continuous. For intermediate temperatures, it is then identified a critical point that separates the abrupt and continuous behaviors. It is also investigated how intrinsic space-charge oscillations may drive stationary states unstable in certain parameter regimes. The results are verified with N-particle self-consistent simulations. V C 2014 AIP Publishing LLC. [http://dx.

HIF research on the University of Maryland Electron Ring (UMER)

“…The first pictures of beam transport over a significant distance are shown in Fig. 3 [20]. Although we were able to transport the beam over half of the first turn with no significant problems, the phosphor screen photos indicate a number of problems.…”

Scaled electron experiments at the University of Maryland

“…For example, many of the important characteristics of the beam transport can currently be measured only by employing the intersecting diagnostics relevant to the first turn alone [1,[10][11][12]. Beam emittance, mismatch, the consequences of skew errors in the magnets, and transport in the beam source and injection region, as well as the characteristics of the injection ''Y'' itself, are suitable for first-turn measurement using intersecting diagnostics such as the insertable phosphor screens.…”

Scaled Models: Space-Charge Dominated Electron Storage Rings

“…As we discovered, the grid significantly affects the beam dynamics near the cathode, where the particles are moving at low energies. A significant outcome of the grid is the formation of oscillating virtual cathodes [22] accompanied by a hollowed velocity distribution, first measured experimentally with a pepper-pot [23]. This behavior has been demonstrated using high-resolution particle simulations using the WARP code [24], which draw heavily upon advanced techniques such as adaptive mesh refinement [22].…”