Beam halo imaging with a digital optical mask

Abstract

Beam halo is an important factor in any high intensity accelerator. It can cause difficulties in the control of the beam, emittance growth, particle loss, and even damage to the accelerator. It is therefore essential to understand the mechanisms of halo formation and its dynamics. Experimental measurement of the halo distribution is a fundamental tool for such studies. In this paper, we present a new high dynamic range, adaptive masking method to image beam halo, which uses a digital micromirror-array device. This method has been thoroughly tested in the laboratory using standard optical techniques, and with an actual beam produced by the University of Maryland Electron Ring (UMER). A high dynamic range (DR $ 10 5 ) has been demonstrated with this new method at UMER and recent studies, with more intense beams, indicate that this DR can be exceeded by more than an order of magnitude. The method is flexible, easy to implement, low cost, and can be used at any accelerator or light source. We present the results of our measurements of the performance of the method and illustrative images of beam halos produced under various experimental conditions.

Photocathode quantum efficiency mapping at high resolution using a digital micromirror device

“…The optical arrangement is similar to that previously reported for beam halo imaging [14]. A simplified experimental schematic is shown in Fig.…”

Nonlinear dynamics with space-charge in a small electron recirculator

“…Left: Result of WARP simulation of excitation of a quadrupole envelope mode in UMER [6]. Right: fluorescent screen pictures of 6.0 mA mismatched beam with (right) and without (left) DMD mask; deep red indicates higher intensity [7]. y x 32 mm…”

“…We have also studied envelope-mismatch induced halos by using a digital micro-mirror device (DMD) to enhance the dynamical range of fluorescent screen diagnostics [7,8]. The DMD contains about 1 M addressable Figure 3.…”

Beam Instrumentation and Diagnostics for the LHC Upgrade

“… Core masking and standard cameras (possibly with adaptive masks based on micro mirror arrays) [11].  Performing an X-Y scan of the image plane with a photo-detector located behind a pinhole.…”