Speaker
Riccardo Nocentini
(ITER Technology and Diagnostics)
Description
The test facility ELISE (Extraction from a Large Ion Source Experiment) at IPP Garching, Germany, aims to demonstrate ITER-relevant negative ion beam parameters which are required for the NBI system of ITER. ELISE is equipped with a Radio Frequency driven source and an ITER‑like extraction system with half the ITER size. An H-- or D-- beam can be extracted for 10 s every 3 minutes from the continuously operating plasma source. The duration of the beam pulses is currently limited by the power supplies available at IPP. Although up to now record-setting 1 hour plasmas have been produced in H-- as well as in D--, long plasma pulse operation with multiple beam blips showed a key issue: the co-extracted electron current during the extraction phase is strongly dynamic and temporally instable, particularly in D--. These instabilities are likely caused by back-streaming ions and Cs dynamics in the source [1]. In order to investigate the source physics in long beam pulses, an upgrade of ELISE using a cw high voltage power supply is envisaged. This upgrade requires a new cw diagnostic calorimeter for which a few concepts are being investigated, which make use of several thermocouples, IR thermography and water calorimetry to measure beam intensity, divergence, profile and homogeneity. In addition the suitability of a tungsten wire calorimeter to characterize the cw beam is being examined. Shielding of delicate components in the beam line, e.g. a large DN 1250 mm gate valve, by means of suitable protection scrapers, is being considered. These technical solutions are presented and discussed in the paper.
Keywords: ITER, NBI, Negative Ion Source, RF Source, Beam Calorimeter
[1] Fantz et al, Rev. Sci. Instrum. 87, 02B307 (2016)
Co-authors
Bernd Heinemann
(ITER Technology and Diagnostics, Max-Planck-Institut für Plasmaphysik, Boltzmannstr. 2, 85748 Garching bei München, Germany)
Dirk Wunderlich
(ITER Technology and Diagnostics, Max-Planck-Institut für Plasmaphysik, Boltzmannstr. 2, 85748 Garching bei München, Germany)
Markus Froschle
(ITER Technology and Diagnostics, Max-Planck-Institut für Plasmaphysik, Boltzmannstr. 2, 85748 Garching bei München, Germany)
Riccardo Nocentini
(ITER Technology and Diagnostics, Max-Planck-Institut für Plasmaphysik, Boltzmannstr. 2, 85748 Garching bei München, Germany)
Rudolf Riedl
(ITER Technology and Diagnostics, Max-Planck-Institut für Plasmaphysik, Boltzmannstr. 2, 85748 Garching bei München, Germany)
Ursel Fantz
(ITER Technology and Diagnostics, Max-Planck-Institut für Plasmaphysik, Boltzmannstr. 2, 85748 Garching bei München, Germany)
Werner Kraus
(ITER Technology and Diagnostics, Max-Planck-Institut für Plasmaphysik, Boltzmannstr. 2, 85748 Garching bei München, Germany)
