We are developing a low-level RF (LLRF) controller based on RF System on Chip (RFSoC) for an electron linac. The AMD Zynq RFSoC was employed for this controller, which has a large-scale high-speed FPGA together with high-speed ADCs and DACs (8 channels each). The RFSoC also has an application CPU for Linux and a real-time CPU for time-critical tasks, capable of a 1 kHz repetition rate. A general-purpose pizza-box module with an RFSoC was designed and manufactured, and firmware for LLRF control was developed. This LLRF module will be first utilized for an X-band (11.424 GHz) transverse deflector system* for SACLA. A pulsed X-band RF signal is generated by upconverting a 476 MHz IF signal from the DAC and RF signals from the X-band high-power components are converted to 476 MHz IF signals and digitized by ADCs. The IF signal is converted to a baseband IQ signal and the phase and amplitude are obtained. Since the latency of ADC, DAC, and FPGA is as short as several 100 ns, the intra-pulse feedback control is anticipated to stabilize the phase and amplitude of the acceleration RF field. This presentation will give the design and basic performance of the LLRF controller.

We report our latest progress developing diagnostics using quantum optics-based detection method for determining the spatial properties and current of electron beams. As electrons pass through a dilute vapor of rubidium atoms, their electric and magnetic field perturb quantum states of Rb atoms and change their optical properties. By measuring the polarization rotation due to electron current, we can recreate a 2D projection of the electrons’ magnetic field and determine the electron beam position, size and total current. Our experiment using a 10 ~ 20 keV/110 uA electron beam shows this approach is insensitive to electron energy. Alternatively, using quantum superpositions including highly excited Rydberg states of Rb atoms, we can also measure electric field generated by a travelling electron beam. We reconstructed a 2D profile of a 20 keV/150 uA electron beam and measured its current. These complimentary methods can be particularly useful for real time non-invasive spatial and current characterization of high energy and high current charged particle beams used in various particle accelerators and nuclear physics research.