North RTL 'Grid Scan' Studies

Emma, P.

Stanford Linear Accelerator Center

关键词: Transformations;    Accelerators,Accphy;    43 Particle Accelerators;    Transport Accelerators,Accphy;    Linear Accelerators;   

DOI  :  10.2172/900236
RP-ID  :  SLAC-TN-07-003
RP-ID  :  AC02-76SF00515
RP-ID  :  900236

美国|英语

来源: UNT Digital Library

【 摘 要 】

This study was made in response to screen measurements which indicated an emittance growth of nearly a factor of two within the North RTL or linac girder-1. Betatron oscillations are induced at the beginning of the North RTL to search for gross geometric aberrations arising within the RTL or sector-2 of the linac. The oscillations are induced horizontally and vertically with two X or two Y dipole correctors stepped in a nested loop fashion. In both cases the full set of RTL and first girder sector-2 linac beam position monitors (BPMs) are sampled in X and Y for each corrector setting. Horizontal (or vertical) data from pairs of BPMs are then transformed to phase space coordinates by the linear transformation constructed assuming the transport optics between the BPMs is known. A second transformation is then made to normalized phase space coordinates by using Twiss parameters consistent with the assumed transport optics. By careful choice of initial Twiss parameters the initial grid can be made square for convenience in graphical interpretation. A linear ''grid'' is then fitted to the transformed data points for each pair of BPMs. The area of each grid is calculated and linearity qualitatively evaluated. Furthermore, although not the focus of this study, the beta match at each BPM can be quantified.