Recently, we have demonstrated new methods to actively stabilize multi-way laser coherence states in the dimensions of time, space and spectrum, so that we can effectively combine many laser beams into one in each dimension. This paper summarizes many of our technical approaches and milestones, from optical physics modeling, to FPGA based feedback control platform, to machine learning pattern...
We propose a new algorithm for calibrating the beam phase that utilizes the steady-state RF forward signal (Vf) in closed-loop operation, which overcomes the difficulties associated with measuring the beam phase using RF transients in open-loop operation in high-intensity proton accelerators. The new algorithm calibrates the beam phase by comparing the steady-state Vf vector before and after...
Precisely determining the gap voltage and phase in an RF cavity is essential for the calibration of the LLRF feedbacks. Following the conventional approach, measured RF power is converted into gap voltage, assuming a given shunt impedance. However, power and impedance evaluations can both have large uncertainties. Alternatively, the voltage can be obtained precisely with a complementary...
Industrial particle accelerators inherently operate in much dirtier environments than typical research accelerators. This leads to an increase in noise both in the RF system and in other electronic systems. Combined with the fact that industrial accelerators are mass produced,, there is less attention given to optimizing the performance of an individual system. As a result, industrial systems...
A direct RF feedback loop has been implemented in the digital LLRF of ALBA aimed to reduce the effective impedance of the RF cavities and so, reduce the beam loading effects. A sample of the cavity voltage signal is added to the PID loop generated signal with adjustable gain and phase shift. The resulting signal is then feed back to the amplifier by means of a DAC and an up-conversion stage....
During the pulsed operation of the linear accelerator in DCLS (Dalian Coherent Light Source), we found a strong correlation between the klystron modulator’s high voltage and the klystron output microwave, with noticeable jitter among adjacent microwaves. Therefore, we propose an intra-pulse feedforward algorithm and implement it in LLRF (Low-Level Radiofrequency) systems. This algorithm...
In 2023, we will replace the LLRF system for the KEK-PF 2.5 GeV ring. The new system is composed of digital boards such as eRTM, AMC, and μRTM, based on the μTCA.4 standard. For our application, development time and cost were minimized by customizing the LLRF technologies developed for the SPring-8 and J-PARC. In our system, we adopted the non-IQ direct sampling method for RF detection. We set...
High Demand for stability, accuracy, reproducibility and monitoring capability were placed on accelerators LLRF systems, because of fundamental and applied experimental requirements. Meanwhile, availability of FPGA boards became better during last two decades. Nowadays, it is possible to implement FPGA based LLRF feedback using boards with low-bandwidth ADC&DAC (down-conversion...
The RF field's quality in particle acceleration significantly affects beam properties. Controlling and measuring the field as observed by the beam is crucial, but only indirect measurements are usually available. In many RF accelerators, a single RF source drives multiple cavities to reduce costs. The individual cavity fields are probed and combined to regulate the vector sum. Errors in...
