As the China Spallation Neutron Source (CSNS) Phase II project upgrades beam power to 500 kW, maintaining horizontal beam orbit stability necessitates more precise output current from the main magnet power supplies. The existing control strategy, suited for 100 kW extraction power, falls short of the higher precision requirements for the output current, characterized by a quasi-sinusoidal waveform with 25 Hz and its higher-order harmonics. Moreover, this strategy is highly sensitive to environmental temperature, causing significant fluctuations in the amplitude and phase of the high-order harmonics, thereby adversely affecting the power supplies' performance. This paper proposes a new control scheme that merges high-order harmonic current compensation with double PI closed-loop control, enabling up to sixth harmonic control in the main magnet power supplies. Leveraging the existing Digital Power Supply Control Module (DPSCM) controller in the power supply system, this approach achieves precise and efficient control of the 50 Hz harmonic current output which was previously the source of the largest ripple error. The study confirms that the new control scheme effectively mitigates temperature drift issues and reduces the output ripple of the entire 50 Hz reference current waveform. As a result, the performance of the main magnet resonant power supplies in Rapid Cycle Synchrotron is significantly enhanced, leading to a marked reduction in the variation of beam orbit deviation.

The main ring (MR) of the Japan proton accelerator research complex (J-PARC) delivers the high-intensity proton beams to the T2K long-baseline neutrino experiment. To observe charge-conjugation and parity-transformation violation in the lepton sector with high accuracy, the upgrade of the MR toward the beam power of 1.3 MW is mandatory. The magnet power supply system of MR was upgraded for this purpose during the long-term shutdown period in FY2021. However, the asymmetry of the closed-orbit distortion (COD) was observed after the upgrade. The cause of the asymmetry was attributed to the large ripples of the excitation currents for the bending magnets. The measures to reduce the ripples were applied to six identical power supplies for the bending magnets, and then the asymmetry was successfully corrected. This result suggests the tune region of the stable beam operation is expected to be improved since the effect of the non-structure resonance should be suppressed. This presentation reports the scheme of the ripple reduction for the excitation currents of the bending magnets and the measurement results of the COD in the MR.

The APS Upgrade (APS-U) multi-bend acromat storage ring requires 1000 high-stability unipolar magnet power supplies. A precision current measurement and calibration system has been developed to independently measure the power supply output current to ensure the accuracy and repeatability of the supplies. The measurement system uses custom commercial DCCT current transducers along with APS-U-designed electronics. The calibration system is designed to perform on-demand calibration of all 1000 DC measurement channels simultaneously using a single current reference source instrument. The calibration system includes a precision current multiplier and impedance buffer based on a novel use of DCCT technology that provides a local precision calibration current for up to 6 DCCTs in series through multi-turn low impedance calibration windings. All system components have been received and passed acceptance testing; the full system is currently being installed in the new storage ring and full-scale evaluation will begin in early 2024. This paper describes the system design and presents preliminary test results.

The High Energy Photon Source (HEPS) is the fourth-generation synchrotron photon source. Compared with the third-generation synchrotron photon source, the brightness is 100-1000 times higher, and the electron emittance of the storage ring is low to the diffraction limit of light. Through physical calculations, it is required that the stability of the storage ring quadrupole magnet power supply be better than 10ppm, and the accuracy of output current be better than 80ppm. This high demand for technical parameter poses a challenge to the development of high precision and stability power supplies. The main circuit topology of the power supply adopts a phase shifted full bridge soft switching scheme, which avoids interference caused by switching noise and improves power stability and efficiency. The high-precision digital power supply controller based on FPGA improves the sampling speed and control accuracy of the power supply, and the constant temperature control circuit ensures that the output current of the power supply meets the requirements of HEPS for power supply performance. In the batch testing section, a testing facility was built to test the stability, accuracy, repeatability, voltage ripple, and other parameter of high precision and stability power supplies. After a year and a half of testing, the performance tests of 1066 power supplies, including linear accelerators power supplies, booster power supplies, storage rings power supplies, dipole and quadrupole combined power supplies, dipole and quadrupole power supplies, were completed. The results all met and exceeded the design specifications. The HEPS high precision and stability power supply meets the design requirements in terms of current stability, accuracy, repeatability, voltage ripple, and other aspects. The batch test results show that the power supply performance using the full bridge phase shifting soft switching technology combined with high-precision digital controller scheme is excellent, and the power supply consistency is good, providing a guarantee for the successful operation of HEPS in the future.

The high-energy photon source (HEPS) under construction in Beijing is an excellent photon source with an emissivity better than 60pm rad. HEPS adopts on axis injection. The fast pulse power supply for booster injection adopts a topology structure of LC resonant discharge based on heavy hydrogen thyristor. The energy storage scheme of pulse capacitors adopts a design scheme of DC charging. The local control station of the fast pulse power supply for the enhancer is mainly responsible for the timing control, charging control, interlock control, protection of the kicker, and remote control. Fast pulse power supplies have high reliability, which poses challenges to the development of local control stations for fast pulse power supplies. The local control station adopts a high-performance programmable logic controller (PLC) as the control core, and applies standard modbus and ethernet for communication protocol to control equipment. A local control station prototype has been built. Through system joint testing, the designed local control station can achieve power control and protection, remote control of the local station, and interlocking protection of the magnet power supply.

Nowadays, the real-time control is more and more popular in the particle accelerator field because it is a powerful tool for stable operation and beam loss suppression in the particle accelerator. However, in the Japan Proton Accelerator Research Complex (J-PARC) Main Ring (MR), real-time control has not been widely used in magnet power supplies yet. Magnet power supplies are very easily affected by disturbances from external factors, such as environmental temperature, device aging, power grid voltage and current fluctuations, and so on. Therefore, it is worth developing a real-time digital controller with general functions for the magnet power supplies to observe and suppress these disturbances. In this paper, we propose the design of a general-purpose intelligence controller for the magnet power supply realized by a System-on-Chip (SoC) Field Programmable Gate Array (FPGA). This digital controller can also be used as a high-resolution data acquisition system, a pattern generator, and a high-precision current control system for magnet power supplies.

This paper presents a study on the upgrade and modernization of the magnet power supplies of the KARA (Karlsruhe Research Accelerator) storage ring. The existing power supplies, which have been in operation for more than two decades, were facing obsolescence and operational limitations. To ensure the continued availability and reliability of the facility for the next decade and beyond, a comprehensive refurbishment was required. The project involved the replacement and upgrade of the power supplies for the dipole and sextupole magnets at KARA, as well as for the dipole and quadrupole magnets in the booster. A key aspect of this modernization effort beside an improvement in efficiency and stability is the migration from a custom control system to EPICS running embedded on the power supplies. This paper provides an in-depth analysis of the motivations, goals, and technical aspects of the power supply modernization project as well as first measurements with the new power supplies and the project status.

This paper investigates the design and implementation of a TPS correction magnet power supply using a combination of a linear power operational amplifier (PA05) and a pre-regulator voltage controller. The PA05 linear power operational amplifier features bipolar output, high internal power dissipation, and wide bandwidth. Utilizing a DCCT sensor as a current feedback element integrated with the pre-regulator voltage controller, a closed-loop current modulation circuit is formed, providing the variable voltage required by the linear power operational amplifier. We have successfully developed a prototype of a linear power operational amplifier power supply with a pre-regulator voltage controller for TPS correction magnets through these measures. Design validation is achieved through control loops, resulting in fast and stable output current performance. The output current ripple is maintained below 100 μA, and the rise time during the step response is 75 μs. During the frequency response test using a 0.1 V interference signal, the gain margin remained within -3 dB at an 11.2 kHz bandwidth, and the phase margin was within -45 ° over a range of 5.1 kHz. The long-term stability of the output current is maintained at ten ppm. Finally, a hardware prototype circuit is assembled in the power laboratory with input voltage ranging from ±24 V, an output current of ±20 A, and a maximum rated power of 240 W.

In this paper, the focus is on the development of a bipolar high-current correction magnet power supply for the future TPS-II permanent magnet corrector coil. The maximum output current of the prototype is speci-fied as 20 A, operating at a voltage of 48 V. This con-figuration enhances the amplitude of the trim magnetic core correction magnetic field, thereby providing greater flexibility in manufacturing the permanent magnet corrector coil. The Danisense DP50-IP-B DCCT is the current feedback component to design a power supply with high current and stability. MOSFETs are configured in a full bridge setup serving as power switches. The driving frequency is set at 40 kHz. Analogue modulation control circuitry and pro-tection circuits ensure precise current control loop modulation. Finally, a hardware prototype circuit is constructed in the power supply laboratory with an input voltage of 48 V, an output current of 20 A, a maximum power of 960 W, and the current ripple com-ponent maintained within 400 μA. This validates the control loop design of the prototype, demonstrating the capability to achieve rapid and stable output cur-rent performance. The small-signal bandwidth tested using a 1V input reference signal shows a -3 dB band-width of 8.51 kHz. Long-term current stability is with-in ±10 ppm, and the interface is compatible with exist-ing TPS correction magnet power supply interfaces, allowing for direct operation within the current sys-tem.

The Spallation Neutron Source (SNS) employed over 200 cold plates in its Injection Kicker and quadrupole power supplies for semiconductor cooling. Each cold plate consisted of an aluminum base with interconnected copper tubes that were brazed together. Unfortunately, the durability of these plates was compromised over time due to corrosion of the copper tubes by de-ionized water. This corrosion led to the formation of small pinhole leaks, which became increasingly problematic in recent years, causing more frequent leaks and subsequent operational downtime for the SNS system. To tackle this issue, a novel solution was pursued involving the incorporation of stainless-steel tubes in the redesign. Two types of cold plates underwent rigorous simulations and extensive testing. One of the redesigned cold plates demonstrated competitive performance and was identified as a feasible replacement option. Consequently, a comprehensive initiative was executed to replace all cold plates.

The Linac Coherent Light Source II (LCLS-II) at the SLAC National Accelerator Laboratory represents a groundbreaking advancement in the realm of Free Electron X-Ray Laser (XFEL) science. This 1.3 GHz continuous-wave superconducting RF LINAC is designed to generate 4 GeV electron bunches up to one MHz, propelling the capabilities of XFEL sources. Achieving a significant milestone, the LCLS-II successfully reached its 2K operating temperature with the first electrons in October 2022, culminating in the generation of the first x-rays in September 2023. This paper offers an overview of the diverse array of DC magnet power supplies (PSs) employed in LCLS-II, which can be categorized into two sections: warm and superconducting. The warm section comprises of two crucial types of PSs-intermediate and trim. Notably, these PSs are subjected to tight stability requirements as low as 20 ppm. The warm section has close to 600 PSs. In the superconducting section, an extra level of complexity is added by including a quench protection circuit to protect the magnets in case of a sudden loss of superconductivity. PSs in this section also have a stability requirement of 0.02 %. The superconducting section has 105 PSs. This paper also discusses the system design and performance of these PSs.