Abstract
The main ECRH scenarios for the W7-X Stellarator are described. Both X2 (low and moderate densities) and O2 scenarios (high density) have been studied. Since O2 scenario cannot be realized without pre-heating, transition from X2 to O2 scenarios has been discussed. Due to a lack of Ohmic transformer, only ECCD is available for compensating the bootstrap current and for controlling the edge rotational transform value. The efficiency of ECCD for all main scenarios has been estimated. All simulations have been performed by a 1D transport code coupled self-consistently with ray-tracing code.
Highlights
The W7-X stellarator [1] is a large-scale device (R0 5.5 m, and a 0.53 m) with superconducting coils and without an ohmic transformer
Due to a lack of Ohmic transformer, only electron cyclotron current drive (ECCD) is available for compensating the bootstrap current and for controlling the edge rotational transform value
High-density regimes above the X2 cut-off density, from 1.2 × 1020 m−3 to 2.0 × 1020 m−3, are accessible with the multi-pass scheme at the 2nd harmonic of the ordinary mode (O2 scenario)
Summary
The W7-X stellarator [1] is a large-scale device (R0 5.5 m, and a 0.53 m) with superconducting coils and without an ohmic transformer. For low and moderate densities up to ne < 1.2×1020 m−3, the main heating scheme is low-field-side launch of the RF beams at the 2nd harmonic of the extraordinary mode (X2 scenario). The main heating scenarios for W7-X with the X2- and O2-modes are investigated by means of predictive simulations using a 1-D transport code [4] coupled self-consistently with the ray-tracing code TRAVIS [5]. Compensation of the bootstrap current by electron cyclotron current drive (ECCD) is considered. The modeling is performed for the “standard” magnetic configuration optimized for confinement
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
