The nonresonant perturbation theory based field measurement and tuning of a linac accelerating structure

R&D of C-Band Accelerating Structure at SINAP

“…The prototype structure is based on constant impedance structure, and is used to learn the RF design, fine fabrication, tuning and high power test [4,5]. Based on the experience of prototype structure, new C-band accelerating structure is optimized with better beam quality, higher power efficiency [6].…”

Numerical studies on tuning of a traveling wave bunching-cum-accelerating structure in simulation environment

“…This section briefly discusses the basic theory of the tuning methodology, which is typically applied experimentally to tune the linac and is available in literature [5,6,[8][9][10][11][12][13][14]. The methodology discussed here is particularly applicable for a structure consisting of non-identical cells, as in the case of bunching-cum-accelerating structure.…”

“…The paper is organized as follows. In section 2, we present a re-cap of the Steele's bead-pull perturbation technique and the tuning method [5,6,[8][9][10][11][12][13][14]. The step-wise algorithm that has been adopted in this paper to tune the linac in the simulations has been elucidated there.…”

“…Shi et al applied the technique for tuning of X-band prototype accelerating structure for CLIC project at CERN, where cell by cell tuning was performed for the desired phase advance [8]. Fang et al tested the feasibility of the method for C-band TW linac for Shanghai soft X-ray FEL test facility [9]. The method was extended to the coupler cells by Shi et al for tuning of X-band TW linac of CLIC at CERN [10], where the machining error in the output coupling iris was corrected by tuning the last cell of linac and its preceding cell, to nullify the reflections.…”

Design, fabrication and cold-test of an X-band accelerating structure for linearizer

“…In the tuning process, the S-parameter and standing wave ratio (SWR) of the whole accelerating structure are measured by vector network analyzer and the electric field distribution is obtained by the bead-pull method, which is a non-resonant perturbation way to revise the frequency of each cell one by one and a non-contact method to reduce friction damage in inner wall [7]. The couplers should be adjusted carefully to minimize the reflection from the output and the global S-parameter by tuning the coupling cell and its adjacent cell.…”