[en] The RF system of CYCIAE-100 cyclotron has two cavities, which are driven separately by two identical 100-kW RF amplifiers.Due to the power on sequence issue of the three DDSs in the LLRF systems, each time when the system is individually switched on, the phase relationship may not satisfy the requirements of beam acceleration. Instead of adding an extra reset logic to the system, a search and validation algorithm based on the decision tree has been carried out to make sure the phase of the two cavities is correct right after applying power to the cavities, taking advantage of existing hardware resources. In the first year of operation, there are more than 20 times of scheduled shutdown of the cyclotron system. For each time when the cyclotron RF system is completely shutdown and powered on again, the operator confirmed that the phase matching of the two cavities can be done automatically within 30 s. The related work, including the optimization of the phase detector and the development and validation of the algorithm, is reported in this paper. (authors)

[en] The Beijing Radioactive Ion-beam Facility project is being constructed by BRIF division of China Institute of Atomic Energy. In this project, a 100 MeV high intensity compact proton cyclotron is built for multiple applications. The first successful beam extraction of CYCIAE-100 cyclotron was done in the middle of 2014. The extracted proton beam energy is 100 MeV and the beam current is more than 20 μA. The RF system of the CYCIAE-100 cyclotron includes two half-wavelength cavities, two 100 kW tetrode amplifiers and power transmission line systems (all above are independent from each other) and two sets of Low Level RF control crates. Each set of LLRF control includes an amplitude control unit, a tuning control unit, a phase control unit, a local Digital Signal Process control unit and an Advanced RISC Machines based EPICS IOC unit. These two identical LLRF control crates share one common reference clock and take advantages of modern digital technologies (e.g. DSP and Direct Digital Synthesizer) to achieve closed loop voltage and phase regulations of the dee-voltage. In the beam commission, the measured dee-voltage stability of RF system is better than 0.1% and phase stability is better than 0.03°. The hardware design of the LLRF system will be reviewed in this paper.

[en] The CYCIAE-230 cyclotron is a proton beam accelerator that is dedicated to proton therapy. In order to meet the requirement of the cavity Dee voltage stability, RF frequency stability and acceleration voltage amplitude balance of the accelerator RF system, a set of low level RF (LLRF) system including the digital-analogue type amplitude loop, the digital tuned loop and the digital voltage balance loop was developed. The LLRF system communicates with the host computer through the serial port to realize the local debugging, and the communication between the LLRF system and the PLC network is realized by using the Profibus-DP communication protocol. The low power desktop experiment and the joint debugging were completed on an experimental cavity with a reduced scale oxygen-free copper. The validity of the voltage balance algorithm was validated, and a key start of the LLRF system was realized without human intervention. The LLRF system satisfies the demand of high frequency system. (authors)

[en] A new double-gap buncher is designed for the CYCIAE-10 cyclotron in order to get the high-intensity proton beam with the order of mA. RF simulation is carefully performed to achieve a deep quantitative analysis of the equivalent capacitance and electrical field distribution. Uniform electrical field technology is verified by EM field simulation to get an electrical field uniformity of 94.67%. Type L matching circuit is used to transfer the loading reactance to 50 Ohms. Variable vacuum capacitor with 5-50 pF is selected for its small power loss and the convenience of commissioning. Dynamic calculation of the buncher and mechanical design are also presented in this paper. The open-loop bench test shows that 370 V_peak RF voltage is established in the central electrode with power consumption of 37 W. Alternative redesign and online test are carried out, and more than 1 mA H^- beams are achieved on the inner target, which verify the buncher design. (author)

[en] We introduce an agent-based model, in which agents set their prices to maximize profit. At steady state the market self-organizes into three groups: excess producers, consumers and balanced agents, with prices determined by their own resource level and a couple of macroscopic parameters that emerge naturally from the analysis, akin to mean-field parameters in statistical mechanics. When resources are scarce prices rise sharply below a turning point that marks the disappearance of excess producers. To compare the model with real empirical data, we study the relationship between commodity prices and stock-to-use ratios in a range of commodities such as agricultural products and metals. By introducing an elasticity parameter to mitigate noise and long-term changes in commodities data, we confirm the trend of rising prices, provide evidence for turning points, and indicate yield points for less essential commodities. (paper: interdisciplinary statistical mechanics)