Transport in JET H-Mode Plasmas with Beam and Ion Cyclotron Heating
Ion Cyclotron (IC) Range of Frequency waves and Neutral Beam (NB) injection are planned for heating in ITER and other future tokamaks. It is important to understand transport in plasmas with NB and IC to plan, predict, and improve transport and confinement. Transport predictions require simulations of the heating profiles, and for this, accurate modeling of the IC and NB heating is needed. Experiments were performed in JET comparing NB and IC heating in Type I ELMy H-mode plasmas in which the NB heating power PNB was reduced when the IC power PRF was turned on, keeping the total approximately constant. An example is shown in figure 1. The IC heating scheme was minority heating of trace H ions resonant at 42.5MHz (WIC ~ WH) near the plasma axis. The antenna set included the A2 and ILA systems. The plasma current was 2.5MA and the toroidal field 2.6 T. The total heating power was approximately twice the LÆH threshold power. The experiment and an initial analysis of the transport and confinement has been described by Versloot, et al. The analysis used the JETTO transport code with PENCIL for the NB heating and PION for the IC heating. Since that paper, measurements have been improved, and a more rigorous transport analysis has been performed. The new results show that both the ion and electron energy transport and confinement are degraded in the NB + IC phase. In both NB and NB + IC phases the ion energy transport is larger than the electron transport. The purpose of this paper is to describe the new analysis and results. Verification, validation, and implications for ITER are discussed.