High-power test of a C-band linear accelerating structure with an RFSoC-based LLRF system

Journal Article · Wed Apr 23 00:00:00 EDT 2025 · Review of Scientific Instruments

DOI:https://doi.org/10.1063/5.0258520· OSTI ID:2572067

Liu, C. ^[1]; Ruckman, L. ^[1]; Herbst, R. ^[1]; Palmer, D. ^[1]; Borzenets, V. ^[1]; Dhar, A. ^[1]; Amirari, D. ^[2]; Agustsson, R. ^[2]; Berry, R. ^[2]; Nanni, E. ^[1]

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1. SLAC National Accelerator Laboratory (SLAC), Menlo Park, CA (United States)
2. RadiaBeam Technologies, LLC, Santa Monica, CA (United States)

Normal conducting linear particle accelerators consist of multiple rf stations with accelerating structure cavities. Low-level rf (LLRF) systems are employed to set the phase and amplitude of the field in the accelerating structure and to compensate for the pulse-to-pulse fluctuation of the rf field in the accelerating structures with a feedback loop. The LLRF systems are typically implemented with analog rf mixers, heterodyne-based architectures, and discrete data converters. There are multiple rf signals from each of the rf stations, so the number of rf channels required increases rapidly with multiple rf stations. With a large number of rf channels, the footprint, component cost, and system complexity of the LLRF hardware will increase significantly. To meet the design goals of being compact and affordable for future accelerators, we have designed the next-generation LLRF (NG-LLRF) with a higher integration level based on RFSoC technology. The NG-LLRF system samples rf signals directly and performs rf mixing digitally. Further, the NG-LLRF has been characterized in loopback mode to evaluate the performance of the system and has also been tested with a standing-wave accelerating structure, a prototype for the Cool Copper Collider (C³) with a peak rf power level up to 16.45 MW. The loopback test demonstrated amplitude fluctuation below 0.15% and phase fluctuation below 0.15°, which are considerably better than the requirements of C³. The rf signals from the different stages of the accelerating structure at different power levels are measured by the NG-LLRF, which will be critical references for the control algorithm designs. The NG-LLRF also offers flexibility in waveform modulation, so we have used rf pulses with various modulation schemes, which could be useful for controlling some of the rf stations in accelerators. In this paper, the high-power test results at different stages of the test setup will be summarized, analyzed, and discussed.

• Research Organization: SLAC National Accelerator Laboratory (SLAC), Menlo Park, CA (United States)
• Sponsoring Organization: USDOE Office of Science (SC)
• Grant/Contract Number: AC02-76SF00515
• OSTI ID: 2572067
• Alternate ID(s): OSTI ID: 2574588
• Journal Information: Review of Scientific Instruments, Journal Name: Review of Scientific Instruments Journal Issue: 4 Vol. 96; ISSN 1089-7623; ISSN 0034-6748
• Publisher: American Institute of Physics (AIP)
• Country of Publication: United States
• Language: English

Related Subjects

Colliders
Control theory
Feedback control system
Field programmable gate array
Linear accelerators
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Signal processing method