Search

Pulse Step Modulation (PSM) based High Voltage Power Supplies (HVPSs) are widely used in fusion research and other applications viz. broadcast transmitters, particle accelerators and neutral beam injectors because of inherent advantages of modular structure, high accuracy and efficiency, low ripple and fast dynamics. Typical Ion Cyclotron Radio Frequency (IC RF) system composed of cascaded connection of Driver stage (130 kW RF output) and End stage (1500 kW RF Output) would need two power supplies. A novel concept of tapping two outputs from single PSM based HVPS is attempted for the first time. PSM based 3 MW HVPS is developed with dual output to feed anode voltage of Driver (up to 18 kV) and Final Stage (up to 27 kV). Controller for the HVPS is designed to suit requirements during local operation and remote operation. In Local operation mode, protection interlocks with in the HVPS are integrated while remote mode has additional interlocks from IC RF Amplifiers system. Field integration of the controller is achieved through fiber optical links to avoid Electro-Magnetic interferences. Present article discusses initial experience of dual output HVPS with IC RF amplifiers, pre-integration validation campaigns including qualification for energy limits. The paper also presents the performance of HVPS at full rated capacity of 2800 kW continuous duty to support 1.5 MW IC RF system.

A Dual output (27 kV & 15 kV), 3 MW Ion Cyclotron High Voltage Power Supply (IC-HVPS) has been installed and integrated with a Diacrode based RF source to be used for ICRF (Ion Cyclotron RF) system. The IC-HVPS Controller is based on LabVIEW Real-time PXI controller, which supports all control and monitoring operations of the PSM based power supply. The controller supports all essential features like, fast dynamics, low ripple and protection for source and loads. EPICS (Experimental Physics and Industrial Control Systems) is an open source software widely accepted in scientific community as supervisory distributed control system including CODAC (Control, Data Access and Communication) for ITER. However interface with LabVIEW RT systems is not fully mature yet. Evolving interface requirements of platforms like EPICS with IC-HVPS control has been assessed and implemented for monitoring purpose. A test case was implemented to identify compatibility, feasibility, consistency and performance of EPICS server with Input Output Controller (IOCs) implemented in Real-time controller. This paper discusses integration of EPICS IOCs and LabVIEW based Real-time Controller along with an analysis on limitations imposed by such integration.

The realization of the ITER Neutral Beam Test Facility (NBTF) and the start the experimental phase are important tasks of the fusion roadmap, since the target requirements of injecting to the plasma a beam of Deuterium atoms with a power up to 16.5 MW, at 1MeV of energy and with a pulse length up to 3600s have never been reached together before. The ITER NBTF, called PRIMA (Padova Research on ITER Megavolt Accelerator), is hosted in Padova, Italy; it includes two experiments: MITICA, the full-scale prototype of the ITER injector and SPIDER, the full-size negative ion source. The realization promoted by the ITER organization is carried out with the contribution of the European Union, channeled through the Joint Undertaking for ITER (F4E), of the Consorzio RFX which hosts the Test Facility, the Japanese and the Indian ITER Domestic Agencies (JADA and INDA) and several European laboratories, such as IPP-Garching, KIT-Karlsruhe, CCFECulham, CEA-Cadarache. The early start of operation of PRIMA experiments is urgent because sufficient experimental time is necessary to face and solve the issues related to the achievement of the desired performance in time for the ITER operation, requiring NBI since the beginning. Substantial progresses have been recently achieved: the buildings construction, begun in October 2012, has been completed by the end of 2015 and the installation of some components has been started since the end of 2014. The SPIDER realization is well advanced: the installation phase is proceeding in good agreement with the general plan; it is expected to be almost completed by the end of 2016. In parallel, the commissioning of the SPIDER power supply (PS) and auxiliary plant systems is being proceeding. Tests at full power and remote control are planned, including also those addressed to reproduce the grid breakdowns and to test the relevant protections. The design of the MITICA injector components was completed in 2015their procurement is being made through a number of tenders, some of them already launched. The HV Power Supply system of the MITICA 1MV accelerator, provided by JADA, was delivered on site in December 2015. The challenging installation of these components, including the step-up transformers and the SF6 gas insulated transmission line, started soon after and will go on throughout 2016. The present phase, with the PRIMA buildings continuously filled with new components, with the installation activities progressing and with also the commissioning and testing phase starting represents a substantial step forward toward the main target. The paper will describe the main challenges the Project Team has dealt during this phase and the important feedback derived for the ITER HNB systems both from the technical and the organizational standpoints.

The diagnostic neutral beam (DNB) line shall be used to diagnose the He ash content in the D–T phase of the ITER machine using the charge exchange recombination spectroscopy (CXRS). Implementation of a successful DNB at ITER requires several challenges related to the production, neutralization and transport of the neutral beam over path lengths of 20.665 m, to be overcome. The delivery is aided if the above effects are tested prior to onsite commissioning. As DNB is a procurement package for INDIA, an ITER approved Indian test facility, INTF, is under construction at Institute for Plasma Research (IPR), India and is envisaged to be operational in 2015. The timeline for this facility is synchronized with the RADI, ELISE (IPP, Garching), SPIDER (RFX, Padova) in a manner that best utilization of configurational inputs available from them are incorporated in the design. This paper describes the facility in detail and discusses the experiments planned to optimise the beam transmission and testing of the beam line components using various diagnostics.

The RF heating and current drive (H&CD) systems to be installed for the ITER fusion machine are the electron cyclotron (EC), ion cyclotron (IC) and, although not in the first phase of the project, lower hybrid (LH). These systems require high voltage, high current power supplies (HVPS) in CW operation. These HVPS should deliver around 50 MW electrical power to each of the RF H&CD systems with stringent requirements in terms of accuracy, voltage ripple, response time, turn off time and fault energy. The PSM (Pulse Step Modulation) technology has demonstrated over the past 20 years its ability to fulfill these requirements in many industrial facilities and other fusion reactors and has therefore been chosen as reference design for the IC and EC HVPS systems. This paper describes the technical specifications, including interfaces, the resulting constraints on the design, the conceptual design proposed for ITER EC and IC HVPS systems and the current status.

The RF heating and current drive (H&CD) systems that are to be installed in ITER during the construction phase, are the electron cyclotron (EC) and ion cyclotron (IC) systems. They are complex assemblies of high voltage power supplies (HVPS), RF generators, transmission lines and antennas. Their design and integration are constrained by many interfaces, both internal, between the subsystems, and external, with the other ITER systems. In addition, some components must be compatible with a nuclear environment and are classified as Safety Important Component. This paper describes the processes implemented in ITER to ensure proper integration.

An ion extractor system has been designed for the steady state superconducting tokamak (SST-1) neutral beam injector (NBI) for an experiment using a prototype ion source with fully integrated regulated high voltage power supply (RHVPS) and data acquisition and control system (DACS) developed at Institute for Plasma Research (IPR) to obtain experience of NB operation. The extractor system is capable of extracting positive hydrogen ion beam of ∼10 A current at ∼20 kV. This paper presents the beam optics study for detailed design of an ion extraction system which could meet this requirement. It consists of 3 grid accel–decel system, each of the grid has 217 straight cylindrical holes of 8 mm diameter. Grids are placed on a specially designed G-10 block; a fiber reinforc plastic (FRP) isolator of outer diameter of 820 mm and 50 mm thickness. Provisions are made for supplying high voltage to the grid system through the embedded feed-throughs. Extractor system has been fabricated, mounted on the SST-1 neutral beam injector and has extracted positive hydrogen ion beam of 4 A at 20 kV till now.

We present characteristics of a 5 MW ion source for SST-1 neutral beam injector. Before the source could be tested for its performance, it was conditioned by 480 arc discharges of 1 s and beam extraction of hydrogen species at various beam voltages ranging between 19 kV and 56 kV. Breakdown free beam extraction could be secured only after about 3000 beam second extraction. The ion source is capable of delivering 1.7 MW of neutral beam power at 55 kV with horizontal and vertical focal length of 5.4 m and 7 m respectively. Beam divergence is ∼0.97°. Steady-state beam energy of 31 MJ at 41 kV was achieved during 14 s long beam extraction. We have not noticed any deterioration of beam parameters, including beam divergence during long pulse operation. These results indicate that 0.5 MW of neutral beam power at 30 kV required for heating of plasma in SST-1 can be delivered.

Multisecondary transformers are used at the input stage of modular high voltage power supplies. These power supplies are used in various steady state and pulsed applications, typical examples are neutral beam injectors, rf and microwave devices [N. Tomljenovic et al., Solid power supplies for Gyrotron and NBI sources, Fusion Technol., 1992; H.-U. Boksberger et al., The solid state TEXTOR high voltage neutral beam accelerator power supplies, in: Proceedings of the 11th SOFE, Austin, 1985, p. 679]. This paper presents a systematic study of the interactions of the transformer secondary winding stray capacitances [S. Austen Stigant, The J&P Transformer Book, Butterworths, London, 10th ed., pp. 498–500] and their behavior on the switching frequency of the power supply. Results from simulation and experiments on a pair of 300 kV A, 415/330 V (20 secondaries), 30 kV dc isolation transformers used for generating a regulated 14 kV dc, 35 A output are presented. Additional dielectric losses ∼13% of the total transformer loss and voltage swings at the switching frequency of the semiconductor devices are observed. Possible effects on the performance of the transformer and the design considerations are discussed. Constructional features and other observations related to the multisecondary transformers are also discussed.

The paper presents the complete engineering design of steady neutral beam injector, with emphasis on the deviation in the design from conventional short pulse injectors.

This paper presents the control system overview, hardware, software and network for Data acquisition and Control system for steady state neutral beam injector (NBIDACS) to be used for heating of plasma in steady state superconducting tokamak (SST-1). The task for NBIDACS is not only to safely deliver 1.7 MW of neutral beams at 55 keV H° a period of 1000 s with 16.7% duty cycle but also to acquire the data related to house keeping of the system and its auxiliaries and diagnostics which determine the quality and parameters of the beam. Major issues concerning the design of the system stem from operation duty cycle of 1000 s ON/5000 s OFF. This calls for use of intelligent techniques not only for managing a large amount (100 MB) of data per shot but also to obtain failsafe, reliable control system and to archive the recorded data.