Beam-target interaction experiments for bremsstrahlung converter applications

Abstract

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Observation of the Dynamics of a Focal Spot Using a Long-Pulse Linear Induction Accelerator

“…A possible way to address ion backstreaming is by elimination of surface contamination before a shot. In [8] and [9] in order to reduce the rate of beam defocusing, precleaning of the target surface with a high-power laser pulse was proposed. This approach requires additional efforts to introduce high-power laser radiation to the target chamber and is associated with a number of obvious technical difficulties.…”

“…The effect of target surface quality on beam focusing was studied in [7]. To reduce the rate of beam defocusing on the target, it was proposed [8], [9] to clean the surface in advance using a high-power laser pulse.…”

Analytic Scalings of the Constant-Neutralization Beam Envelope Equation, with Applications

“…Since the partial neutralization of the beam changes its focusing characteristics on the target, and since the high extraction energy means the ion column is moving rapidly into the beam and introducing strong time variation, this "backstreaming ion" phenomenon has been an area of active study in the transport of the high-intensity electron beams used in radiographic accelerators (see [2] for an example of such machines). However, much of the work has been experimental [3] and numerical [4]. The conceptual understanding provided by pencil-and-paper analysis thus far [5,6] has covered the important topics (such as disruption length and neutralization fraction, to be defined later) but generally in the context of idealized beam envelopes that lack enough detail to examine the "control knobs" in a focusing system, such as focal length, time-varying magnetic lenses, or time-averaged focusing.…”