Spherical Tokamak Plasma Science and Fusion Energy Component Testing

Abstract

＊＊＊＊＊ Non-memberRecent progress (1) in plasma science of the Spherical Tokamak (or Spherical Torus, ST) (2) has indicated relatively robust plasma conditions in a broad number of topical area including strong shaping, stability limits, energy confinement, self-driven current, and sustainment. This progress has enabled an extensive update of the plasma science and fusion engineering conditions of a Component Test Facility (CTF), which is potentially a necessary step in the development of practical fusion energy. The chamber systems testing conditions in a CTF are characterized by high fusion neutron fluxes Γ n > 4.4×10 13 n/s/cm 2 , over sizescale > 10 5 cm 2 and depth-scale > 50 cm, delivering > 3 accumulated displacement per atom (dpa) per year (4) . Such chamber conditions are calculated to be achievable in a CTF with R 0 = 1.2 m, A = 1.5, elongation ~ 3, I p ~ 9 MA, B T ~ 2.5 T, producing a driven fusion burn using 36 MW of combined neutral beam and RF power. The ST CTF will test the life time of single-turn, copper alloy center leg for the toroidal field coil without an induction solenoid and neutron shielding, and require physics data on solenoid-free plasma current initiation, ramp-up, and sustainment to multiple MA level. A new systems code that combines the key required plasma and engineering science conditions of CTF has been prepared and utilized as part of this study. The results show high potential for a family of relatively low cost CTF devices to suit a range of fusion engineering science test missions.

Discharge Characteristics of Large-Area High-Power RF Ion Source for Positive and Negative Neutral Beam Injectors

“…Three long-pulse ion sources (LPIS-1, -2 and -3) of the NBI-1 system consist of a magnetic bucket plasma generator with multi-pole cusp fields, a filament heating structure, and a set of tetrode accelerators with circular apertures. There are development and testing plans for the large-area test-RF ion sources at KAERI to extract the positive ions, which can be used for the second NBI (NBI-2) system of KSTAR, and to extract the negative ions for future fusion devices such as a Fusion Neutron Source and Korea-DEMO (or Asia-DEMO) [7,8] .…”