Development and benchmark with experiemental results of predictive models of extraction and acceleration of high power negative ion beams

Project leaders

Vanni Antoni, Yasuhiko Takeiri

Agreement

GIAPPONE - JSPS - Japan Society for the Promotion of Science

Call

CNR/JSPS 2012-2013

Department

Energy and Transportation

Thematic area

Engineering, ICT and technologies for energy and transportation

Status of the project

New

Research proposal

The Neutral Beam Injector (NBI)  is a key component of the thermonuclear experiment ITER under construction in Cadarache (France) as an International cooperation involving, among others, Japan and EU. The NBI is based on an electrostatic accelerator and a radiofrequency negative ion source which have to deliver 40A of negative ions accelerated to an energy of 1 MeV for one hour. The unprecedented level of current and voltage makes the development of the NBI for ITER a challenging task. EU and Japan share the development of such device. CNR is in particular deeply involved in the project through Consorzio RFX and the construction of the related Test Facility in Padova at the CNR site which will host the prototype of the NBI in order to test and optimize it before the construction of the NBI system to be installed in ITER. In parallel to the development of the NBI, the preparation of the Operation Team and of the necessary tools is in progress for an efficient exploitation of the Test Facility. To this purpose several numerical codes are in use or under development at Istituto Gas Ionizzati aimed to describe the extraction and the optics of the negative ion beam. These codes require a careful validation with experimental data in order to provide reasonable confidence in extrapolating the results to regimes of currents and voltages not explored so far. At NIFS three NBI's based on negative ions are at present in operation on the device LHD together with a complementary Test Facility which provide at the moment the only systems operating for long pulses at power levels of the order of MW's. A collaboration between the two institutions can offer therefore a unique occasion to benchmark the results of the simulation codes at Istituto Gas Ionizzati with the experimental results at NIFS as well as to carry out field tests of the existing prototypes of the diagnostic systems planned for the ITER NBI Test Facility. The result of the research is expected to highlight the role of CNR in the key subject of the negative ion physics relevant for the realization of an efficient neutral beam system for ITER and future fusion reactor.

Research goals

Complete the set of exisiting numerical codes wchich include atomic physics relevant for the process of extraction and steering: production of secondary particles by bombardment of primary particles ( negative and positive ions and electrons) of materials exposed to the beam and by interaction of beam particle with background gas.
Application of the numerical codes  to the experimental results provided by the NBI systems in operation in the LHD device at NIFS by tuning the energy and currents to the standard experimental parameters of the beam.
Extended eperimental scan in parameters ( particle energy and current) to validate the model
 
 

Last update: 21/05/2024