1. Advanced tokamak investigations in full-tungsten ASDEX Upgrade.
- Author
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Bock, A., Doerk, H., Fischer, R., Rittich, D., Stober, J., Burckhart, A., Fable, E., Geiger, B., Mlynek, A., Reich, M., Zohm, H., and ASDEX Upgrade Team
- Subjects
COLLISIONAL plasma ,HEAT flux ,TOKAMAKS ,PLASMA flow ,TUNGSTEN ,PLASMA currents - Abstract
The appropriate tailoring of the
q -profile is the key to accessing Advanced Tokamak (AT) scenarios, which are of great benefit to future all-metal fusion power plants. Such scenarios depend on low collisionalityν * which permits efficient external current drive and high amounts of intrinsic bootstrap current. At constant pressure, lowering of the electron densityn e leads to a strong decrease in the collisionality with increasing electron temperatureν * ∼ T e − 3 . Simultaneously, the conditions for lown e also benefit impurity accumulation. This paper reports on how radiative collapses due to central W accumulation were overcome by improved understanding of the changes to recycling and pumping, substantially expanded ECRH capacities for both heating and current drive, and a new solid W divertor capable of withstanding the power loads at lown e . Furthermore, it reports on various improvements to the reliability of theq -profile reconstruction. A candidate steady state scenario for ITER/DEMO (q 95 = 5.3,β N = 2.7,f bs > 40%) is presented. The ion temperature profiles are steeper than predicted by TGLF, but nonlinear electromagnetic gyro-kinetic analyses with GENE including fast particle effects matched the experimental heat fluxes. A fully non-inductive scenario at higherq 95 = 7.1 for current drive model validation is also discussed. The results show that non-inductive operation is principally compatible with full-metal machines. [ABSTRACT FROM AUTHOR]- Published
- 2018
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