A study is conducted on the influence of radio frequency (rf) waves upon interchange stability in HANBIT mirror plasmas. An emphasis is put on the interchange stability near the resonance region, ω0 ≃ Ωi, where ω0 (Ωi) is the angular frequency of the applied rf wave (ion cyclotron frequency). A strong nonlinear interaction between the rf wave and the interchange mode has been observed with the generation of sideband waves. A theory of rf-interchange mode interaction keeping effects of both the equilibrium ponderomotive force and the nonlinear sideband wave coupling is applied to interpret HANBIT experimental results, resulting in good agreement. Results have shown that the nonlinear coupling process is responsible for the rf stabilization of interchange modes near the resonance region.

KOreOTo understand the edge plasma fluctuation in the central cell region of Hanbit mirror device, the Visco-Mach probe is used to measure the parallel and poloidal velocity along the field. The Visco-Mach probe was attached on the fast injection system, which can scan the central cell region of Hanbit device in the radial direction. Also to calculate the driving force of plasma flow, ErxB, the emissive probe is used t o measure the plasma potential. The experimental data from the Visco-Mach and emissive probe will be presented and driving force of the plasma flow will be discwed along with the velocity of Mach probe thwry atomkwakQihanyang.ac.kr 7PA41 Design consideration on ex-vessel neutron yield monitor for ITER' K. Asai('), T.Ignchi('), and T.Nishitani(') ( I ) Gmduote School of Engineering, Department of Nuclear Engineering, Nagoya Unitiersity. Fum-ehou,ChJcusn-ku, Nagoya-shi Aichi 464-8603, JAPAN (' ) Japan Atomic Energy Reseorrh Institute Tokai-mum, Nok-gun,lbamki 319-1195, JAPANNeutron yield measurement is one of the most important plasma diagnostic system in DD and/or DT fusion experiments and allows an absolute measure of the fusion power. In ITER experiments, main characteristics required for the neutron yield monitor ' are (1)real-time measurement(1m time resolution), (2)stable and robust operation with high-reliability and redundancy in a hostile environment, (3)neutron-gamma rays discrimination characteristic, (4)wide dynamic range(from 8 to 11 orders of magnitude) and (5)appropriate detection efficiency characteristic for absolute measurement of total neutron yield, which means as a flat energy detector response as possible. To meet these requirements, we propose a neutron yield monitor based on U-235 fission chambers with neutron moderators to be installed outside the vacuum vasel, which is routinely used at other tokamaks. We use graphite as the neutron moderator in view of the thermal resistance. Fig.1 shows a structure of the present detector module. The thickness of the paphite moderator was designed to obtain the flat energy detector response, as shown in Fig.2. The dynamic range of a single detector can be extended up to 9 orders in combined operation of counting and Cambering modes, which is well established as nuclear instrumentation for fission reactors. The location of the detector modules must be decided to monitor the whole phase of ITER operation, including in-situ calibration using a DD /DT neutron generator. We are planning t o install a pair of the detector modules in the two equatorial ports (named as #S and #17), respectively. To guarantee a reasonable count rate around lcps during the calibration, one of the detector modules should be placed as close to plasma as possible. From the configuration of ITER #S and #17 ports, we selected 2 locations; one is just behind the limiter module and another at 30cm of neutron shield made of 70% SUS and 30% H 2 0 behind the former one. By making good use of 8 detecton with different sensitivity in this location, it is pcxssible to cover all ...