Schulze, Martin E. | Search NASA

DOE OSTI2023

New Collins Quad Design

The Collins quadrupoles are used on the DARHT 2nd axis to transform the elliptical beam from the septum quadrupole back to a round beam. They are also used to minimize kicker smear by producing a point-to-point focus from the kicker to the target. The present Collins quads introduce significant aberrations due to the design of the iron pole tip. The effect of these aberrations becomes particularly large as the beam size in the Collins quads increases. This note describes an improved 2D pole tip design for the Collins quads developed using POISSON.

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DOE OSTI2023

Magnetic-Field Diffusion Effects in Beam Position Monitors III: Application to DARHT-II Beam Data

Beam position monitors (BPMs) provide time-resolved measurements of the current and centroid position of high-current electron beams in linear induction accelerators (LIAs). One of the types of detectors used in BPMs is the B-dot loop, which generates a signal from the EMF due to the time varying magnetic flux through the loop. If some of the boundaries of the loop are composed of thick metal walls with finite conductivity, the resulting signal must be corrected for the magnetic field diffusion into the metal. The theoretically predicted flux due to diffusion is in remarkable agreement with experimental measurements. Although accurate BPM measurements of beam current require correction of magnetic field diffusion, accurate measurement of beam position requires no correction. In this note, we present experimental validation of current and position results from a prototype detector employing finite conductivity sensing areas, based on experiments on the DARHT-II LIA.

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