An Indian test facility to characterise diagnostic neutral beam for ITER

Online tuning of impedance matching circuit for long pulse inductively coupled plasma source operation—An alternate approach

“…They provide very efficient, economical and technologically simple way of producing high density uniform plasmas in field of semiconductor [3,4] and fusion technology [5,6]. In fusion grade machines, neutral beam injector (NBI) systems and its related R&D facilities in Europe [7] and in India [8], ICP based negative ion sources are planned to be used due to its low maintenance requirements [9,10]. Geometrical parameters like length, diameter and number of turns of the coil antenna play a big role in coupling RF power into the plasma in ICP [11].…”

“…In low power ICPs, it is normally done with measuring reflected power from the load using directional coupler in a feedback mechanism. In fusion grade ion source operation [7,8], such online methodology is not present but remote tuning by adjusting the driving frequency of the RF generator between the ion source operation pulses is envisaged A set of analytical formulation is presented based on air core transformer model [12,13,14]. In the model, RF antenna coil is considered as transformer primary coil and the plasma as the single turn secondary coil.…”

RF generator interlock by plasma grid bias current – An alternate to Hα interlock

“…directional coupler. However, in case of vacuum immersed RF ion source in reactor grade NBI system (TWIN source [16,17] and INTF [18,19], such plasma light based interlock may not be feasible due to lack of adequate optical fiber interfaces in the design.…”

Can we estimate plasma density in ICP driver through electrical parameters in RF circuit?

“…However, in the respective test stands, SPIDER & MITICA, for testing Heating and Current Drive (H&CD) NBIs [11] and INTF for Diagnostic Neutral Beam (DNB) [12], the plasma in the ion sources will be adequately characterized by standard electrostatic probes and optical emission spectroscopic methods. During NB operation in ITER, online plasma characterization in the ion source will be useful to optimize the beam operation and related trouble shooting.…”