Array of Metallic Posts: Possible Application for Beam Position Monitoring

Abstract

It is proposed to utilize the diffraction radiation emitted by an electron traversing an array of metallic posts for deducing the electron's displacement from the symmetry axis of the structure. In other words, it is proposed to use such an array as a beam position monitor (BPM). The structure consists of a set of N N u metallic vertical posts bounded from above and below by two horizontal metallic plates. The beam position offset from the symmetry axis is determined by measuring the backward radiation emitted by the beam as it traverses the array. The position resolution of the suggested BPM is dominated by the noise level of the detectors used for measuring the radiation, whereas the time resolution is dominated by their operation frequencies.

Summary Report of Working Group 7: Electromagnetic-Structure Based Accelerators

“…B. Cowan described use of deflection-mode PBG structures for beam position detection. S. Banna presented a metallic-post array BPM [15]. The pickup is a phased array antenna optimized to radiate in the backward direction (giving easy separation of signal and electron beam), with the difference in the relative strengths of the "left" and "right" lobes giving information about the beam's horizontal position.…”