Extraction Power Supply Research Articles

The extraction of both positive and negative ions from a volume cusp H− ion source

The TRIUMF licensed H− ion source is known to produce 15 mA of H− ions, but some applications, such as cyclotrons, require the injection of both positive and negative ions. Furthermore, when using a tandem accelerator, there would be a benefit in using an ion source that can directly extract H− and He+. A charge exchange chamber would only have to be used with the He+ beam for the production of He−. In this paper, we present the conversion of the H− ion source to allow for the extraction of both positive (He+, H+, H2+ and H3+ ) and negative (H− and D−) ions. In the modified design, up to 3 mA of protons and 2 mA of He+ can be extracted when using positive extraction power supplies and up to 5 mA of H− can be extracted when the polarity of the power supplies switched to negative extraction. We study how the ion source parameters affect the proton fraction and we look at the influence of the magnetic filter field in the plasma chamber.

Modelling activity in support of MITICA high voltage system protections

MITICA, the full-scale prototype of ITER Heating Neutral Beam (HNBs), has challenging requirements on its power supplies. In particular its unconventional high voltage system is designed to operate at high power and voltage (up to -1 MV dc and about 54 MW), with many interfaces and high voltage insulation technologies co-existing in a single plant. Moreover, the electrical system must manage frequent breakdowns between the accelerator grids during the operation, creating electrical fast transients characterized by extremely high voltage and current peaks. In the conceptual design phase suitable design provisions were conceived to limit the energy in the grids and to limit the overvoltage on specific components in the case of grids-breakdown. The integration tests of the power supplies showed the capability of the system to generate and sustain voltage as high as 700 kV; at higher voltage the voltage withstanding capability was not confirmed as some breakdowns occurred in the plant. Although the location of the breakdowns has not been identified yet, an impact of such breakdowns was highlighted as a couple of the components of the plant suffered a damage. This paper is focused on the analyses performed for the understanding of the fault occurred on the secondary bushing of the 1 MV insulating transformer dedicated to the supply of the Ion Source and Extraction Power Supply system (ISEPS). An extensive activity of modelling and simulation has been developed for explaining the dynamic occurred. The model is based on the stray parameters of the components, which were not easy to be estimated in the design phase, but which turn out to have relevant effects in local fast transient phenomena. After reaching a full understanding of the phenomena, the models have been used to support the conceptual design of an additional protection system for the transformer, for MITICA but also in view of the ITER installation.

SPIDER ion source and extraction power supplies - An update of the design of the bias circuits after four years of operation

SPIDER, the ion source prototype for ITER neutral beam injectors, has been in operation since 2018. The experiment includes a system of Ion Source and Extraction Power Supplies (ISEPS), whose design dates back to 2011. Since then the experience gained has led to substantial changes, the most dramatic modification being the complete replacement of the radiofrequency power supply, described elsewhere. This contribution details operating experience and calculations that have led to defining new requirements for a specific subset of power supplies, the bias power supplies.The bias power supplies perform the function of filtering out electrons extracted together with the negative ions and in the original 2011 ISEPS design are single quadrant resonant converters. For the two bias power supplies, the picture resulting from the review described in the paper is a substantial redesign, with the ability to operate in four quadrants and a twofold increase of the rated output voltage the most significant new specifications.

Optimal design of energy-taking power supply based on AC electric field induction

AC electric field induction based energy extraction power supply is a new power supply method for the on-line monitoring device of transmission lines, but because of its low output power, it is difficult to meet the electricity demand of the on-line monitoring device. In order to solve this problem, a new induction electrode structure is proposed based on the theoretical analysis of the factors affecting the energy taking power, and the simulation analysis and experimental verification are carried out. The results show that the designed induction electrode can generate a displacement current of 3.35mA at 10kV voltage level, and the power output can be more than 600mW when the load resistance is greater than 5kΩ. The principle and method of this paper provide a new idea for solving the power supply problem of on-line monitoring device.

Electrostatic Simulation and Analysis of Transmission Line Corner Section for the CRAFT NNBI Test Platform

The gas-insulated transmission line (GITL), which is an important link between ion source and the power supply system, carries all the ion source and the extraction power supplies (ISEPS) conductors at −400 kV with respect to ground, from high voltage deck (HVD) to the ion source and the intermediate potentials of acceleration grids (AGs). In this article, three insulation schemes of the corner section of the GITL are put forward. Through the finite element analysis, only one scheme satisfies the design requirements. In this analysis, the relationships between the design parameters (the radius and angle of the corner section) and the design guiding principles (maximum electric field strength, equivalent distributed capacitance, and so on) are obtained. According to design requirements, the preliminary design parameters of the corner section are determined: the radius of the corner section can change from 50 to 150 mm and the angle of the corner section is chosen as 90°. In this case, the maximum electric field strength of the GITL decreases from 3.18 to 3.06 kV/mm, the maximum electric field strength of the inner surface of the grounding shell decreases from 1.08 to 0.73 kV/mm, the electric field non-uniformity coefficient decreases from 2.21 to 2.15, and the equivalent distributed capacitance increases from 82.12 to 94.70 pF. The simulation results provide a theoretical basis for the engineering design of the corner section of the GITL.

Power supply system for large negative ion sources: Early operation experience on the SPIDER experiment

In the road-map for a fully operational ITER Neutral Beam Injector (NBI), SPIDER represents a necessary step to test its negative ion source design since the required performances have never been achieved simultaneously by any previous experiment. The smaller scale of SPIDER to the full ITER NBI prototype (named MITICA, which will operate in the same test facility in Padova) allows more flexibility in the experiments and, taking advantage of its larger set of diagnostic, will provide insightful results for the entire project development.This paper is the result of the experience gained within the first two years of SPIDER operation, with the focus on the Ion Source and Extraction Power Supply (ISEPS) system. A review of the system development, of the main outcomes of the first experimental phase and the description of the still open issues, is provided.

射频负离子源引出电源控制和采集系统设计

射频负离子源引出电源控制和采集系统设计

Design and Test of the Interlock Protection System for Extraction Power Supply of Negative Ion Source at ASIPP

Negative ion beam source test equipment, currently under construction at Institute of Plasma Physics, Chinese Academy of Sciences, is a prototype of a radio-frequency (RF) ion source for neutral beam injection. An extraction grid power supply (EGPS) for the RF ion source is utilized to extract negative ions. To acquire the output of the EGPS and assure its safe operation, an interlock protection system has been designed. The system meets the requirements of anti-interference signal transmission and management of fast protection in order to minimize adverse consequences. The system takes care of breakdowns occurring during normal operation. All the required functions are implemented by hard-wired circuits, so the response time of fault protection can be less than . This technical note describes the rationale of the isolated transmission and protection functions and presents the implementation of functions in the detailed design. System performance during the experimental tests is described, with emphasis on demonstration of the protection.

The development of data acquisition and control system for extraction power supply of prototype RF ion source

A 16 kV/20 A power supply was developed for the extraction grid of prototype radio frequency (RF) ion source of neutral beam injector. To acquire the state signals of extraction grid power supply (EGPS) and control the operation of the EGPS, a data acquisition and control system has been developed. This system mainly consists of interlock protection circuit board, photoelectric conversion circuit, optical fibers, industrial compact peripheral component interconnect (CPCI) computer and host computer. The human machine interface of host computer delivers commands and data to program of the CPCI computer, as well as offers a convenient client for setting parameters and displaying EGPS status. The CPCI computer acquires the status of the power supply. The system can turn-off the EGPS quickly when the faults of EGPS occur. The system has been applied to the EGPS of prototype RF ion source. Test results show that the data acquisition and control system for the EGPS can meet the requirements of the operation of prototype RF ion source.

The Transmission Line for the SPIDER Experiment: From design to installation

SPIDER (Source for the Production of Ions of Deuterium Extracted from RF plasma) is the full scale prototype of the Ion Source for the ITER 1MeV Heating Neutral Beam Injector (HNB) and is presently under construction in the Neutral Beam Test Facility at Consorzio RFX premises, in Padua, Italy. The required Ion Source and Extraction Power Supply (ISEPS) system and the associated diagnostics need to be hosted inside a −100kVdc air-insulated Faraday cage, called High Voltage Deck (HVD); a High Voltage Transmission Line (TL) carries many power and signal conductors from the ISEPS to the Ion Source.An air insulated design of the TL, coping with the large dimensions required to host ISEPS diagnostic and power cables and duly screened against Electromagnetic Interferences (EMI), has been conceived. The paper reports on the construction solutions developed by the Manufacturer to meet the design indications and requirements of the technical specification for such unconventional device. Moreover, the factory type tests to validate the design and release the manufacturing of the overall TL are described. Finally, the paper reports on the on-site installation and commissioning activities for the final acceptance concluded in June 2016.

Development of pulse power supply system based on Marx generator for the arc ion source of the VEST NBI

A short-pulse and high power supply system is developed for the pulse arc ion source of the neutral beam injector (NBI) of the Versatile Experiment Spherical Torus (VEST). The NBI system, with the maximum ion beam power of 20keV, 0.8MW and pulse length of 10ms, was designed for the auxiliary plasma heating and current drive source. However, the beam injection energy needs to be lower than 20keV under the initial target plasma parameters of VEST due to the beam-plasma coupling efficiency. For this reason, modulation of the beam energy in pulse duration is important to increase efficiency of the VEST NBI system. To satisfy these requirements, a pulse power system based on Marx generator is developed by utilizing high-energy capacitors and a solid-state switching system for the ion beam extraction and arc power supply. In addition, a battery-based power supply system is developed for the filament heating power supply which is highly cost-effective. In this paper, circuit structure and features of the power supply system of the ion source for the VEST NBI is described and the results of the discharges test are presented.

Study on the microwave ion source of the 100-MeV proton linac

A microwave ion source is used as an ion source of 100-MeV proton accelerator at Korea Multipurpose Accelerator Complex (KOMAC). The specifications of the ion source are 50 keV in energy and 20 mA in peak current. The plasma is operated in CW mode using magnetron and the pulse beam is extracted using semiconductor switch located in the extraction power supply. The beam characteristics were measured based on the pulse voltage and current. A test stand was also installed to study the beam characteristics of the ion source in off-line. In this paper, the pulse beam characteristics of the ion source are presented and the installation of the test stand is reported.

High-voltage terminal test of a test stand for a 1-MV electrostatic accelerator

The Korea Multipurpose Accelerator Complex has been developing a 300-kV test stand for a 1-MV electrostatic accelerator ion source. The ion source and accelerating tube will be installed in a high-pressure vessel. The ion source in the high-pressure vessel is required to have a high reliability. The test stand has been proposed and developed to confirm the stable operating conditions of the ion source. The ion source will be tested at the test stand to verify the long-time operating conditions. The test stand comprises a 300-kV high-voltage terminal, a battery for the ion-source power, a 60-Hz inverter, 200-MHz radio-frequency power supply, a 5-kV extraction power supply, a 300-kV accelerating tube, and a vacuum system. The results of the 300-kV high-voltage terminal tests are presented in this paper.

Design, manufacture and factory testing of the Ion Source and Extraction Power Supplies for the SPIDER experiment

The SPIDER experiment, currently under construction at the Neutral Beam Test Facility in Padua, Italy, is a full-size prototype of the ion source for the ITER Neutral Beam Injectors. The Ion Source and Extraction Power Supplies (ISEPS) for SPIDER are supplied by OCEM Energy Technology s.r.l. (OCEM) under a procurement contract with Fusion for Energy (F4E) covering also the units required for MITICA and ITER injectors. The detailed design of SPIDER ISEPS was finalized in 2011 and manufacture of most components completed by end 2013. The Factory Acceptance Tests took place early 2014. ISEPS, with an overall power rating of 5MVA, form a heterogeneous set of items including solid state power converters and 1MHz radiofrequency generators of 200kW output power. The paper presents the main features of the detailed design developed by OCEM, focusing in particular on the high output voltage pulse step modulators, the high output current resonant converters, the radiofrequency generators by HIMMELWERK GmbH and the architecture and implementation of the complex control system. Details are given on non-standard factory tests verifying the insulation requirements specific to this application. Performance of ISEPS during the factory acceptance tests is described, with emphasis on demonstration of the load protection requirements, a crucial point for all neutral beam power supplies. Finally, key dates of SPIDER ISEPS installation and site testing schedule are provided.

The 100 kV Faraday cage (High Voltage Deck) for the SPIDER experiment

In order to optimize the design and operation of the Ion Source for the ITER Neutral Beam Injector (NBI), a dedicated 100keV Ion Source, identified as Source for the Production of Ions of Deuterium Extracted from RF plasma (SPIDER), is under construction in the Neutral Beam Test Facility, at the Consorzio RFX premises, in Padua, Italy.The Ion Source, polarized at −112kVdc voltage, will produce negative ions (Deuterium D− or Hydrogen H−) which, extracted from the Plasma Grid with an extraction voltage up to 12keV, are accelerated up to 100keV by the 100kVdc Power Supply (100kV PS). The required Ion Source and the Extraction Power Supplies (ISEPS) system and the associated diagnostics are hosted inside a High Voltage Deck (HVD), a −100kVdc air-insulated Faraday cage. These power supplies and various diagnostics and control equipment are connected to the Ion Source by means of a High Voltage Transmission Line (TL).The HVD (procurement started mid 2013; delivery on site in the second half of 2014) will consist of a wide structure (13m (L)×11m (W)×5m (H)), designed to support the weight of the ISEPS components, mounted on supporting insulators and clad with a conductive metal sheet in order to reduce the electromagnetic interference (EMI).The paper reports on the design solutions of the HVD focusing on insulation, mechanical, thermal and EMI issues. The details of the main HVD interfaces with the TL and with insulating transformer are also described.Finite Element (FE) analyses have been performed, on the one hand, to verify the configuration from the electrostatic point of view and, on the other, to evaluate electrical screen effectiveness from the EMI point of view.

Development of the front end test stand and vessel for extraction and source plasma analyses negative hydrogen ion sources at the Rutherford Appleton Laboratory

The ISIS pulsed spallation neutron and muon facility at the Rutherford Appleton Laboratory (RAL) in the UK uses a Penning surface plasma negative hydrogen ion source. Upgrade options for the ISIS accelerator system demand a higher current, lower emittance beam with longer pulse lengths from the injector. The Front End Test Stand is being constructed at RAL to meet the upgrade requirements using a modified ISIS ion source. A new 10% duty cycle 25 kV pulsed extraction power supply has been commissioned and the first meter of 3 MeV radio frequency quadrupole has been delivered. Simultaneously, a Vessel for Extraction and Source Plasma Analyses is under construction in a new laboratory at RAL. The detailed measurements of the plasma and extracted beam characteristics will allow a radical overhaul of the transport optics, potentially yielding a simpler source configuration with greater output and lifetime.

Multi-layered waveguide DC electrical break for the PEFP microwave proton source

A microwave proton source has been developed and is being used for 50-keV proton injection to the 20-MeV proton linac of the Proton Engineering Frontier Project (PEFP). It includes a 2-kW rf system for plasma generation. Because the rf system is electrically connected to a high-voltage beam extraction power supply, it is not easy to operate, control and maintain the rf system on the high-voltage platform. A 50-kV DC break has been developed on the waveguide between the proton source and the rf generator, and has been compared with the waveguide without the DC break. The results show the same operation performances, with very low radiation loss and no electrical breakdown, and will be helpful for easy operation and maintenance of the proton injector for the 100-MeV proton linac.

Technical Design of Arc-Discharge and Deceleration Power Supply for MW Level NBI System on HL-2A Tokamak

Neutral beam injection (NBI) is one of the most effective ways to heat and drive plasma in a tokamak. The mega watt level neutral beam injector on the HL-2A tokamak consists of four high-power ion sources. Each source is supplied by discharge, beam extraction and auxiliary power supplies. Some circuit topologies and control sequences designed for the system are presented in this paper. Some important technologies such as the notching circuit, insulated gate bipolar transistor (IGBT) series-connected switch, high-frequency switching power supply and control system based on a digital signal processor (DSP) have been used. The system can be effectively used for high current ion beam extraction, protection, ion optics and so on. The power system has been safely used in HL-2A high-parameter NBI experiments for three years. The power of NBI can be kept at higher than 0.75 MW for 1 second and the ion beam power extracted from the ion source is higher than 2 MW. The ion temperature of the plasma center is close to 2.0 keV. These results show that the design of this power system is reasonable and reliable, and it can fully meet the system requirements for NBI of the HL-2A tokamak.

Compact microwave ion source for industrial applications

A 2.45 GHz microwave ion source for ion implanters has many good properties for industrial application, such as easy maintenance and long lifetime, and it should be compact for budget and space. But, it has a dc current supply for the solenoid and a rf generator for plasma generation. Usually, they are located on high voltage platform because they are electrically connected with beam extraction power supply. Using permanent magnet solenoid and multi-layer dc break, high voltage deck and high voltage isolation transformer can be eliminated, and the dose rate on targets can be controlled by pulse duty control with semiconductor high voltage switch. Because the beam optics does not change, beam transfer components, such as focusing elements and beam shutter, can be eliminated. It has shown the good performances in budget and space for industrial applications of ion beams.

Optimizing the front end test stand high performance H− ion source at RAL

The aim of the front end test stand project is to demonstrate that chopped low energy H(-) beams of high quality can be produced. The beam line currently consists of the ion source, a 3 solenoid low energy beam transport and a suite of diagnostics. A brief status report of the radio frequency quadrupole is given. This paper details the work to optimize the ion source performance. A new high power pulsed discharge power supply with greater reliability has been developed to allow long term, stable operation at 50 Hz with a 60 A, 2.2 ms discharge pulse and up to 100 A at 1.2 ms. The existing extraction power supply has been modified to operate up to 22 kV. Results from optical spectroscopy measurements and their application to source optimization are summarized. Source emittances and beam currents of 60 mA are reported.