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The extraction grid power supply (EGPS) is important for neutral beam injection of tokamak, which is used to extract the negative ions from the plasma source. A set of power supply with pulse step modulation topology at 16 kV/20 A has been designed for the negative ions extraction at the Institute of Plasma Physics, Chinese Academy of Sciences, which meets the requirements of fast dynamics, low ripple, and good output operation. The development of EGPS is presented in this paper. Two different voltage ratings and series-connected switched power supply (SPS) modules are fed from multisecondary transformer. Insulated-gate bipolar transistors are applied to the switch of SPS module. Rise time and fall time of EGPS out voltage can be set from few microseconds to milliseconds. When the overcurrent occur, the output voltage falls to zero less than $5~\mu \text{s}$. The dynamic performance tests with dummy load of EGPS are presented. The testing results indicate that the power supply meets the demands of negative ions extraction. The design provides a foundation for the next phase of extraction experimental operation for radio frequency ion source. [ABSTRACT FROM AUTHOR]

Indian negative-ion source development program has gained momentum with planned integration of Indian Test Facility (INTF) for International Thermonuclear Experimental Reactor (ITER)—Diagnostic Neutral Beam (DNB) characterization at the Institute for Plasma Research (IPR). Eight RF driver-based negative-ion source, being developed for DNB will be tested and operated in INTF. The Two driver-based Indigenously built Negative ion source (TWIN) source provides a bridge between the operational single driver-based negative-ion source test facility, ROBIN in IPR, and an ITER-type multidriver-based ion source. The source is designed to be operated in continuous mode with 180 kW, 1 MHz, 5-s on/600-s off duty cycle and also in 5-Hz modulation mode with 3-s on/20-s off duty cycle for three such cycles. The complete design of TWIN source and its test facility, from conceptual to detailed engineering, has been carried out in IPR. The manufacturing design has been optimized to match the capability of Indian manufacturers, without compromising on the specifications. Some examples of optimization are: 1) an improvised design of the Faraday shields where electrodeposition has been replaced by vacuum brazing; 2) a simplified design of the side walls of the plasma source, where jointing process is simplified, without the application of Electron Beam Welding; and 3) introduction of a fiber reinforced polymer-based integrated electrical and vacuum isolation scheme that replaces the application of a large ceramic. Finite-element analysis (FEA) based on heat load and structural load calculation ensure the functionality and structural integrity of each component of the source. Due to nonnuclear environment in TWIN source experimental area, vacuum brazing is an acceptable manufacturing process. The contract for manufacturing of the ion source has been awarded to an Indian manufacturing company for the first indigenous production of a large-size fusion grade ion source. TWIN source is designed in such a way that it can be operated both in air mode (RF driver coil antennas are exposed to air) as well as vacuum mode. (Whole source is immersed inside vacuum.) The TWIN source shall be manufactured as per ASME guidelines for pressure vessel. Experiments on the TWIN source are foreseen in the last quarter of 2015, as all the auxiliary systems such as 180-kW, RF generator system, vacuum vessel with pumping station, cooling water system, data acquisition and control system, and other power supply systems are already installed in the lab premises. This paper discusses the FEA-based engineering design, simplified manufacturing design, manufacturing experience with highlighting quality control, and the system integration activities undertaken for the TWIN source test facility. [ABSTRACT FROM PUBLISHER]

Multidriver-based radio-frequency (RF) ion sources have emerged as the most promising option for producing the plasma in large ion sources required for fusion applications. In India, under domestic long-term fusion program, a negative ion source development program has been initiated. A 100-kW inductively coupled single RF driver-based negative ion source (ROBIN) has been installed and it is operational at the Institute for Plasma Research. The next step is to move to a multidriver source and address to several issues related to configuration and operation. A two-driver-based twin source has been configured for this purpose. The experimental plan is divided into two phases: 1) plasma operation phase and beam extraction and 2) acceleration phase. A vacuum chamber has been specially designed to accommodate these phases of operations. The data acquisition and control system (DACS) of the experimental system is designed based on International Thermonuclear Experimental Reactor—COntrol Data Access and Communication (ITER-CODAC) guidelines. Probe and spectroscopy diagnostics constitute the principal diagnostics. This paper presents the experimental system with emphasis on the aspects of mechanical, electrical, and DACS integration. [ABSTRACT FROM PUBLISHER]

The particle-in-cell (PIC) algorithm for the simulation of charged-particle kinetics in plasmas is a very resource consuming method, and high-performance parallel computing is required for practical problems. Graphics processing units (GPUs) are powerful low-cost parallel systems that can be used for intensive computations. We have developed a PIC Monte Carlo collision (MCC) model of a low temperature magnetized plasma using GPUs. We describe how each part of the PIC MCC model is implemented on the GPU and show how particles are dynamically managed. The computational cost of the PIC MCC model on the GPU is compared with a standard PIC MCC model running on a single central processing unit (CPU). We show that speedup can reach from 10 to 20 times compared with a sequential code running on a CPU, depending on the number of cells and particles considered. The results are illustrated with the example of plasma transport across a magnetic filter similar to that of a negative-ion source for the neutral beam injector of fusion devices. [ABSTRACT FROM PUBLISHER]