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P: Fachverband Plasmaphysik
P 4: HEPP II
P 4.2: Vortrag
Montag, 20. März 2023, 16:55–17:20, CHE/0091
3D Monte Carlo PIC modeling of particle extraction from negative ion sources — •Max Lindqvist1,2, Dirk Wünderlich1, Serhiy Mochalskyy1, Adrien Revel2, Tiberiu Minea2, and Ursel Fantz1 — 1Max-Planck-Institut für Plasmaphysik, Garching, Germany — 2Université Paris-Saclay, CNRS, LPGP, Orsay, France
Negative H− or D− ions for the ITER NBI system are produced in RF ion sources, mainly by surface production, and accelerated through a multi-aperture grid system. One of the main limiting factors during operation of such ion sources is the amount of co-extracted e−, in particular during operation with D. For a correct description of the particle dynamics close to the Plasma Grid (PG) where a 3D magnetic field is present, self-consistent 3D PIC-MCC modeling is needed. The 3D PIC-MCC code ONIX has been used to simulate one PG aperture in the ELISE ion source, a half-size ITER-like ion source in IPP Garching. The impact of plasma parameters on the co-extraction of e− is presented. A higher Te has a strong impact on the amount of co-extracted e−. The original code was improved by adding a plasma generation module that allows modeling the biasing of the PG w.r.t. the source walls. By increasing the PG bias above the floating potential, the amount and temporal instability of co-extracted e− are strongly decreased, in agreement with experiments. ONIX was coupled with the beam code IBSimu to allow the correlation of particle properties from the plasma to the beam, and to study the extraction probability and beam divergence of negative ions during different configurations of PG biases and geometries to give insights into grid optimization.