Compact Extraction and Matching System for High Current Accelerator Applications

(In the context of advancing accelerator technologies for societal applications, and within the framework of the European Organization for Nuclear Research (CERN) Knowledge Transfer (KT) initiative, a novel compact beam extraction and matching system (CEMS-02) has been developed. This system aims to enhance the performance and reduce the footprint of injector linac designs for high-current applications. The concept builds on the first version of the Compact Extraction and Matching System (CEMS-01), which was developed for low-current applications, specifically focusing on the extraction of the beam from the plasma and its matching to the first stage of acceleration. CEMS-02 reimagines conventional Low-Energy Beam Transport (LEBT) lines by replacing them with a set of carefully engineered electrodes, thereby achieving significant space savings while improving beam quality. Specifically designed for the Linac4 RF ion source operating in proton mode (IS04), CEMS-02 capitalizes on the source’s capability to deliver beam currents exceeding 60 mA, as well as on the availability of a dedicated test stand replicating Linac4’s LEBT section and providing comprehensive diagnostics. The system consists of five electrodes, including the plasma electrode, within a total length of only 2 cm. This extreme compactness introduces unique challenges, particularly regarding thermal stability and mechanical integrity, since temperature-induced displacements in the extraction region can critically degrade the beam quality. The lossless electrostatic design fulfils three key objectives: efficient extraction of high-current proton beams (> 60 mA), compatibility with the transverse acceptance of the Linac4 Radio Frequency Quadrupole (RFQ), and initial beam acceleration to 45 keV to meet the RFQ injection requirements. This work presents both experimental measurements and simulation studies that partially validate the performance of the CEMS-02 prototype. The demonstrated functionality confirms its potential as a compact, high-efficiency extraction solution and paves the way for its adaptation to other ion sources in a wide range of high-current accelerator