[en] A reactor-heating concept utilizing a wave-guide-launched ion-Bernstein wave in the ion-cyclotron range of frequencies is presented. Details of wave-launching transformation, propagation and absorption, together with low-power experimental results from the ACT-1 toroidal device, are summarized. (author)

No abstract available

[en] A number of recent Tokamaks (PLT, TFR, Erasmus, Macrotor, Caltech) have started investigating ICRF heating generating a fast magnetosonic wave in 3 basic types of conditions: -i- fundamental cyclotron resonance of the majority ion species; in this condition mode-conversion near the inner plasma edge plays an important role; -ii- harmonic resonance in a hydrogen plasma where both electron Landau damping and harmonic cyclotron damping are expected to heat the main body of the plasma; -iii- harmonic resonance in a deuterium plasma, a scenario essentially different from the previous one since it is usually impossible to ignore the interaction of the wave at fundamental resonance with a small amount of hydrogen impurity. In this note we concentrate on scenario no.3 which itself appears to brake into various sub-scenarios depending on the concentration of hydrogen. Indeed the energy of the fast wave may either be directly absorbed by the particles or channel through a mode conversion region and then be transferred to particles via a slow electrostatic mode. Our purpose is to give analytical estimates of the transition between the different regimes of interest and to calculate the combined overall damping of the fast wave

No abstract available

[en] A series of recent papers has established the idea that even a small amount of hydrogen impurity at fundamental resonance in a deuterium plasma modifies entirely the damping mechanism of the fast magnetosonic wave (FMW). The FMW energy is linearly mode-converted into a slow electrostatic mode (EW) in the ion-ion hybrid resonance layer. The overall damping of the FMW eigen modes can be calculted without knowing the fate of the EW. Obviously, the evaluation of the heating performance requires to know the trajectory and damping of the EW which contain the information on the localisation and heating rate of the various plasma species. Perkins has presented preliminary solutions to this problem. In a Tokamak geometry, he showed the paramount importance of the effects of the finite temperature and the poloidal field component normal to the mode conversion layer. In this paper we consider again the same problem but we include the damping effects of the minority species and the integration of the deposited power in each species along the wave trajectory. Moreover we find necessary to solve the wave equation for an arbitrary magnitude of the damping decrement

[en] A complete analysis of an ICRH antenna system is given yielding practical criteria for design optimisation relevant to large machines. After having analysed the screening effect of an electrostatic shield, a solution is presented for the field distribution around an electrostatically shielded antenna from which the effect of the plasma on the loading and the reactance of the antenna can be obtained. A general procedure for the application of these results to multple antennae system is outlined and practical rules are derived for optimizing the rf power unit antenna surface coupled to the plasma

[en] 500 KW, the maximum available RF power, at a frequency of 60 MHz and in 50 to 100 ms pulses, has been launched in TFR plasmas using an array of 4 half turn antennae. The array has a potential power capability of 1 MW through a single port. The electrical coupling efficiency is about 90%

[en] ICRH can be applied at the MW power level to the Wendelstein VII-AS stellarator. This will be the first high power, long pulse experiment in a large stellarator. Minority (H in D) and second harmonic heating of hydrogen will be possible. The technical system is described in detail. (author). 11 refs.; 4 figs

[en] ICRF heating at 2Ω_CH was investigated for a variety of different target plasmas and heating regimes. In all cases a significant increase of the radiated power, caused mainly by a higher iron concentration in the plasma, is observed. Neither the moderately improved particle confinement nor a reduction of impurity screening on account of changed plasma edge parameters is responsible for the high radiation losses, but enhanced wall erosion is required to explain the experimental data. The impurity production mechanisms are not yet fully understood. Impurity sputtering by oxygen and carbon, however, could be experimentally excluded as possible production processes. In all experiments a clear anticorrelation between wave absorption and impurity production was observed. Moreover, we find that suprathermal ions are produced in the plasma edge region by the non-absorbed ICRF power. It is assumed that these particles are responsible for the excessive impurity production. (orig.)

[en] A high power long pulse transmitter whose frequency range is in the range of VHF(Very High Frequency) bands have been widely used for fusion researches and accelerator as well as broadcasting industry. KAERI (Korea Atomic Energy Research Institute) have been developing the transmitters for ICRF heating for KSTAR and the cyclotron accelerator since 1996. The toroidal magnetic field of KSTAR (Korea Superconducting Tokamak Advanced Research) is nominally 3 T so that 25-60 MHz transmitter is required to cover ICRF heating scenarios of the KSTAR. The first one is 2 MW transmitter operating up to 60 MHz and it succeeded in achieving 2 MW for 300 s in 2008 after several failures of tetrode tube at the final amplifier stage. Up to 300 kW RF power was successfully injected to KSTAR plasmas. The second one is the wideband 70 kW/CW transmitter used for the cyclotron accelerator and their frequency range is from 25 to 50 MHz. Its engineering design was finished. The third one is 1 MW/VHF transmitter which was loaned from JAEA. As the operating ICRF frequency of KSTAR is lower than VHF bands, its cavity structure will be modified for KSTAR and the operating frequency would be changed from 110 MHz to 60 MHz. In this presentation, the test results of JAEA transmitter at 120 MHz and lessons from the high power test of 2 MW transmitter will be introduced and the circuit analysis and engineering design work for the second and third amplifiers will be shown.