International Doctoral College in Fusion Science and Engineering
 Thesis catalogue
Study of different RF antenna configurations in Aline reactor to heat ions
PhD Code: 2016-DC-01:
Mobility
  • Host institute 1: FP2-Université de Lorraine (Home University)
  • Host institute 2: FP1-Ghent University (Host University)
  • Host institute 3: FP9-Max-Planck-Institut für Plasmaphysik Garching und Greifswald (Host Institution)
Research fields:
  • F1. Tokamak physics for ITER and beyond
Promotor(s):
  • Prof. Eric Faudot (promotor)
  • Prof. Jean-Marie Noterdaeme (co-promotor)
  • Dr. Rodolphe D''Inca (mentor)
Contact Person and email: Eric Faudot - eric.faudot@univ-lorraine.fr

Subject description
Background: Unresolved hot spot issue on ICRF antenna structures. RF sheath physics and DC potential structure in front of these antennas. Convective cells in front of ICRF antennas. Aline is a magnetized plasma reactor dedicated to RF sheaths studies and RF coupling. The maximum 0.1 T magnetic field allows to excite ion and electron cyclotron resonant frequencies.

Expected outcomes

Objective: Enhancement of ICRF coupling to heat the ions in small plasma discharge reactor in order to match the edge tokamak plasma parameters. The main goal here is to test several RF couplings (capacitive and or inductive) to heat the ions via the ion cyclotron frequency or a hybrid frequency which would be more efficient to initiate the plasma. For the moment Aline is equipped with a capacitive RF antenna which is not able to efficiently ionize the neutral gas far from the radial position of the antenna (several cm only). The new antenna configuration will be able to excite the plasma in the whole chamber and increase the ion energy up to 2 eV or more with 1 kW of rf power. This reactor is presently fully operational with an adjustable magnetic field along the axial direction of the 1 m long cylindrical chamber and the broadband rf amplifier is able to launch rf waves from 10 kHz up to 250 MHz to test different resonant frequencies. The first step of this work will consist in simulating the electric field induced by different inductive antenna geometries at the most relevant frequencies in the COMSOL software. Next the antenna will be designed and built according to mechanical constraints imposed by the vacuum chamber and plasma parameters. In a second step this one will be installed in the vacuum chamber and first measurements with an actuated Langmuir probe should be performed. A coupler is also available to measure the power deposition into the plasma and the reflection coefficient. Time line and mobility scheme (research need to be performed for at least six month in two different countries): Home (IJL) : 24 months half time devoted to ALINE experiments on RF sheath Physics and ICRF coupling (new antenna design and testing) based on the background of Hot plasma team (fluid model, PIC simulations). Host (U. Gent-IPP_G): 12 months devoted to experiment at IPP_G on the real size ICRF antenna to compare plasma parameters (ion temperature especially).

 

Original document: 2016-DC-01



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