Abstract
Matching to small beta functions is required to preserve emittance in plasma accelerators. The plasma wake provides strong focusing fields, which typically require beta functions on the mm-scale, comparable to those found in the final focusing of a linear collider. Such beams can be time consuming to experimentally produce and diagnose. We present a simple, fast, and noninvasive method to measure Twiss parameters in a linac using two beam position monitors only, relying on the similarity of the beam phase space and the jitter phase space. By benchmarking against conventional quadrupole scans, the viability of this technique was experimentally demonstrated at the FLASHForward plasma-accelerator facility.
Highlights
Plasma-wakefield accelerators [1,2,3] can provide accelerating gradients in the GV/m-range [4,5], promising smaller and cheaper accelerators [6,7]
Fast, and noninvasive method to measure Twiss parameters in a linac using two beam position monitors only, relying on the similarity of the beam phase space and the jitter phase space
Since the focusing field from an exposed ion column in a plasma accelerator is typically very strong, beams must be tightly focused for the beam size not to oscillate, as this would lead to significant and unacceptable emittance growth [16]
Summary
Plasma-wakefield accelerators [1,2,3] can provide accelerating gradients in the GV/m-range [4,5], promising smaller and cheaper accelerators [6,7]. Conventional beam-focus diagnostics include wire scanners and high-resolution screens around the focal point, or downstream quadrupoles that point-to-point image the beam onto a screen—all of which require nontrivial experimental setups and careful data analysis. This can be inconvenient when matching beams into a plasma accelerator—a slow multiparameter optimization process where fast feedback will be crucial. While the method is approximate in nature, it allows online monitoring and iterative adjustment of the waist location and beta function This technique was successfully implemented and experimentally demonstrated at the FLASHForward [21,22] plasma-accelerator facility at DESY
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
