A test station for the THALES 300kW transmitter PSM has been successfully constructed in NSRRC. Integrating the modules of power supply, control interface, interlock protection, and accessories into a single rack simplifies the examination procedure and makes signal observation easier. The layout and hardware realization of this test station, as well as important considerations and proper examination procedure in place to ensure safe and accurate operation are all presented in this article.

The National Synchrotron Radiation Research Cen-ter (NSRRC) has developed a 320 kW solid-state am-plifier based on an 80 kW solid-state amplifier. In the design of the 80 kW amplifier, the DC power supply and solid-state amplifier racks were separated, with the DC power supply providing power to the solid-state amplifier power terminals through cables. This separa-tion allows the DC power supply rack to be movable and not take up space in the solid-state amplifier rack. However, this design requires additional ground space to accommodate the DC power supply rack and re-quires significant staff and time to wire the cable con-nections. The 320 kW solid-state amplifier incorporates a bus bar design, which significantly reduces wiring space and time while also having a simpler appearance.

The RF group constructed a second radio frequency (RF) system for the Taiwan Photon Source (TPS) RF system. This RF system employs a high-power RF transmitter to deliver RF energy to the cavity. The RF transmitter is composed of multiple power supply modules (PSMs) that are installed in series. PSMs are critical and fragile components of the RF transmitter. This article presents the maintenance history of PSMs from 2011 to 2022 and provides guidance on how to troubleshoot and diagnose fault problems. Furthermore, this article proposes an improvement strategy for preventing any failure events.

The RF system for storage ring in TPS is adopted two sets of 500 MHz KEKB-type SRF modules, with total operating voltage of 3.2 MV. Its power is provided by two sets of klystron-type transmitters with an output power of up to 300 kW, and the RF feedback loop is controlled by analog LLRF system. Since the RF system started to operate, it has been continuously improved and introduced new technologies and functions. So far, the system is gradually stable, and the mean time between failures is gradually increasing.The construction of TPS phase III is in progress. To meet its power requirements, the third RF station was officially launched in 2018 for a period of five years. The system integration and performance testing were successfully completed in February 2022. However, the performance of the 4.5K LHe cryogenic system tends to degrade with operating time, which resulted in the newly built KEKB-type SRF module to remove from the operation. Subsequently, a scheme of combining two kinds of heterogeneous power sources to increase the operating power of two SRF modules is proposed and is in progress. TPS will be upgraded to the multi-bend achromat storage ring in the future, and the bunch length will become shorter. Thus, the design and manufacture of the third harmonic superconducting passive cavity was officially launched in 2019, and the system integration and testing are expected to be completed in 2024-2025.

The analog LLRF system of the Taiwan Photon Source (TPS) booster ring was replaced by the DLLRF system at the beginning of 2018. The difference between setting points and measured values during the ramping process was controlled within 0.3% and 0.2° for the accelerating field amplitude and phase, respectively. Moreover, the sidebands of 60-Hz noise and their high-order harmonics were suppressed to lower than −70 dBc. However, for the storage ring operation with the DLLRF system, several difficulties have been encountered because of the high bandwidth of the digital controller and the heavy-beam-cavity–LLRF interaction, which may result in an oscillation of the accelerating field. The operation parameters for each RF station, therefore, must be tuned for stable operation under the heavy-beam-cavity–LLRF interaction. A long-term stability test for the DLLRF system was performed in October 2021. Under appropriate operational parameters, the TPS DLLRF system exhibited stable operation at 500 mA.

The low level RF system of TPS booster ring was replaced by the DLLRF in 2018. After that, the phase drift compensation loop for energy saving operation and the tuner loop were also implemented into the DLLRF system sequentially. We used altera-DE3 to build the core of DLLRF and to handle the high speed ADC/DAC procedure for RF signal sampling. As facing to the tuner control requirement, we choose an another low cost board, altera-DE0-Nano, to develop the tuner loop for 5-Cells-Petra-Cavity. It has an eight channels 12-bits-ADC, ADC128S022, to detect two tuners’ positions and two transmit powers for power balance function. The phase information of forward power and cavity gap voltage will get from altera-DE3 to tell the tuner loop in altera-DE0-Nano that the cavity is resonance or not. The tuner loop controls the cavity to work not only at resonance frequency but also with balance electric field distribution. In this study, the architecture of the tuner loop is presented including locking resonance frequency and field balance functions. The performance of field balance function is observed by the archive data of two tuners’ positions and two transmit powers.

The purpose of a Low Level Radio Frequency (LLRF) system is to control the amplitude and phase of the accelerating field in the cavity. To improve the RF field stability and to decrease the noisy sideband such as few kHz sideband from RF transmitter, a study for the application of active disturbance rejection control (ADRC) is ongoing. ADRC algorithm is based on an extended state observer, which can estimate the total disturbance acting on the system and then to cancelled them. The simulation results of the ADRC controller for the Taiwan Photon Source RF system will be reported in this paper.