Overview of recent progress and future in GAMMA 10/PDX project

This paper presents an overview of the recent progress of GAMMA 10/PDX project. In the GAMMA 10/PDX project, development of fusion reactor relevant research related to magnetic mirror devices has been conducted. One of the main objectives is divertor simulation studies under the similar condition of actual fusion devices, which contributes to comprehensive development strategy towards the divertor plasma physics and plasma wall interaction (PWI) studies. The recent progress of this research is that an additional plasma heating (ICRF and ECH) significantly increased the ion flux up to 3.3 × 10²³ /m² s at the end-mirror exit, which proved an effectiveness of additional plasma heating for generating high ion flux from the mirror end. Superimposing a short pulse of ECH produces the maximum heat flux of 21 MW/m² by improving the west plug ECH antenna system, which exceeds the heat-load of ITER divertor plates. In detached plasma formation experiments using the divertor simulation experimental module (D-module), comparison of various radiator gases (Xe, Ar, Ne, N₂) injected into D-module showed that Xe was the most effective gas on electron cooling and reduction of heat and ion fluxes. In the development of high-power gyrotrons, a number of electron cyclotron heating experiments using high-power gyrotrons have been performed under strong collaboration and we made a remarkable contribution to LHD and QUEST. The first 28 GHz MW tube has attained 1.38 MW and new MW-level dual frequency gyrotron test is also in progress and 1.22 MW at 28GHz is achieved. Multi-channel/multi-pass Thomson scattering system has been developed and simultaneous measurement of radially 6 points with 10 Hz can be available. The multi-pass function of this system also improved the measurement accuracy and time resolution. Microwave interferometer system has been developed in the GAMMA 10/PDX end-cell, which contributes to detailed diagnostics for divertor simulation plasmas in D-module.