Steady state tokamak reactor based on the bootstrap current

Abstract

A concept of a steady state tokamak fusion reactor based on the bootstrap current is presented. Operation at high poloidal beta (βp ≥ 2.0) and high q (4–5) with a relatively small limit on ∈βp (< 0.5) makes it possible to drive a bootstrap current constituting up to 70% of the total plasma current without exceeding the Troyon beta limit. The rest of the plasma current can be driven by the high energy neutral beam with an energy multiplication factor Q of 30. Energy confinement scaling laws predict that the reactor condition is attainable by increasing the major radius up to 9 m in such a high βp and high q plasma at a relatively low plasma current (12 MA) with a confinement enhancement factor of 2 compared with the L-mode scaling. This reactor has a reasonable size (Vp = 1500 m3) and fusion output power (2.5 GW) and is consistent with present knowledge regarding tokamak plasma physics, namely the Troyon limit, the energy confinement scalings, the bootstrap current and the current drive efficiency (neutral beam current drive with a total power of 70 MW and a beam energy of 1 MeV) with good prospects for the formation of a cold and dense divertor plasma.

Effect of toroidal field ripple on the formation of internal transport barriers

“…Advanced tokamak scenarios are proposed to provide the conditions needed for a steady-state demonstration in ITER [1][2][3][4][5]. The goal is to reach a high pressure at a modest plasma current where a large fraction of the plasma current is driven by the bootstrap current, providing a noninductive self-generated current.…”

Profile and Shape Control of the Plasmas with Transport Barriers towards the Sustainment of High Integrated Performance in JT-60U.

“…The JT-60U tokamak project has addressed major physical and technological issues in the ITER R&D and in developing commercially attractive steady-state author's e-mail: kamada@naka.jaeri.go.jp reactor concepts such as SSTR [6]. These experimental and demo reactors require simultaneous sustainment of high confinement, high normalized β (β N ), high bootstrap current fraction f BS , full noninductive current drive, high fuel purity, high density, and high radiation fraction (see Fig.…”

A Review of Fusion and Tokamak Research Towards Steady-State Operation: A JAEA Contribution

“…Observation of a high bootstrap current fraction, up to 80% in the JT-60 high-β p discharges [73] stimulated the design development of a SSTR, consistent with updated scientific and technological knowledge at that time [5]. [7].…”

“…This leads to the need for the development of the reactor concept. In 1990, we developed a steady-state tokamak (from the transliteration of the Russian sentence toroidal'naya kamera s aksial'nym magnitnym polem or toroidal chamber with an axial magnetic field) reactor concept called SSTR best utilizing the bootstrap current [5] and its conceptual design [6,7]. The conceptual development of the SSTR (Steady State Tokamak Reactor) was done for this purpose and to implement this philosophy into large tokamak experiments [8].…”

“…The SSTR concept was originally developed in 1989 as a DEMO concept (aiming to demonstrate sustained electric power generation from fusion) with minimum extrapolation from the knowledge in those days [5,6]. A power reactor concept with similar core plasma assumptions but more aggressive technical provisions, ARIES-I [74], was developed independently.…”