Status of the ITER IC H&CD System

Abstract

The ITER Ion Cyclotron Heating and Current Drive system will deliver 20MW of radio frequency power to the plasma in quasi continuous operation during the different phases of the experimental programme. The system also has to perform conditioning of the tokamak first wall at low power between main plasma discharges. This broad range of reqiurements imposes a high flexibility and a high availabiUty. The paper highlights the physics and design reqiurements on the IC system, the main features of its subsystems, the predicted performance, and the current procurement and installation schedide.

Experimental investigation of ion cyclotron range of frequencies heating scenarios for ITER's half-field hydrogen phase performed in JET

“…Considerable RF acceleration of deuterium beam ions was also observed in some discharges of the 3 He heating experiments (where both the second and third harmonic ion cyclotron resonance layers of the D ions are inside the plasma) whilst it was practically absent in the majority hydrogen heating scenario. While hints of improved RF heating efficiency as a function of the plasma temperature and plasma dilution (with 4 He) were confirmed in the H majority case, the 3 He concentration was the main handle on the heating efficiency in the second harmonic 3 He heating scenario.…”

“…This is a rather optimistic statement and is based on the assumption that all the power launched by the ICRF antenna is absorbed in the plasma. In H plasmas and for the designed frequency range of the ICRF heating system in ITER (f = 40-55 MHz) [3], only fundamental ion cyclotron heating of H ions (at f ≈ 40 MHz) and second harmonic (N = 2) ion cyclotron heating of 3 He (at f ≈ 53 MHz) ions are feasible for central ion heating at the nominal half-field value of B 0 = 2.65 T. This is illustrated in figure 1, where the radial positions of the cold ion cyclotron layers of a few ion species are plotted as a function of the RF frequency for the ITER parameters at B 0 = 2.65 T. The continuous lines represent fundamental (N = 1) ion cyclotron resonances, the dashed lines represent the second harmonic (N = 2) resonances and the dotted lines stand for the third harmonic (N = 3) ion cyclotron resonances of the various species. Note that the impurities' resonances (with charge over mass somewhat lower than 1/2) are always located at the high-field side of the machine.…”

A new ion cyclotron range of frequency scenario for bulk ion heating in deuterium-tritium plasmas: How to utilize intrinsic impurities in our favour

“…Furthermore, according to the computed ICRF antenna performance in ITER, the reduction of the plasma coupling if operating at a lower frequency is reasonably small. If compared to the results for the officially approved frequency 40 MHz, the coupled power is lower by about 15% only for f = 38 MHz and by 20% for 37 MHz [24,40,41].…”

“…At first glance, this frequency is not ITER-relevant since the official ICRF range is f = 40 − 55 MHz [24,25]. However, ITER RF generators are foreseen to deliver RF power in the range f = 35 − 65 MHz [39].…”

“…The design of the ITER ICRF system currently envisages the use of two antennas [24,25]. With that, one could imagine several ICRF strategies for the ramp-up phase.…”