The primary goals of the NSTX Upgrade research program include: accessing 3 to 6 times lower collisionality to study confinement (see Figure 1) and stability much closer to ST-FNSF parameters, to access fully non-inductive plasma start-up and sustainment, to develop and utilize high-power long-pulse divertor solutions compatible with high plasma performance, and to continue to support ITER burning plasma research through access to unique parameters regimes, such as strong drive for energetic particle instabilities and transport.
The NSTX Upgrade Project consists of three major
enhancements of the NSTX facility (see Figure 2):
1. A new centerstack (CS) of larger diameter enabling a doubling of the toroidal field (up to 1 Tesla), a tripling of the solenoid flux (up to 2.1 Webers), and up to fives times longer flat-top duration. The new CS also includes additional divertor poloidal field (PF) coils to improve power exhaust capabilities and coaxial helicity injection (CHI) efficiency.
2. A second Neutral Beam Injector (NBI) to double the NBI heating and current drive power (up to 10MW for 5s) while aiming more tangentially to provide a factor of 1.5-2 times higher current drive efficiency and improved control of the NBI-driven current profile. A large penetration in the vessel wall and a new port are required for this more tangential NBI.
Many diagnostic and rack relocations are also required in the NSTX test-cell to provide sufficient floor space for the second NBI and associated high-power electrical equipment (see Figure 3)
3. Substantial structural enhancements to the toroidal field coils, poloidal field coils, the vacuum vessel, and vacuum vessel supports to withstand electromagnetic loads up to four times higher than NSTX resulting from the simultaneous doubling of the toroidal field and plasma current (up to 2MA).
For additional technical information on the NSTX Upgrade project see the following links: