Page 8 - Characterization and calibration of the Thomson scattering diagnostic suite for the C-2W field-reversed configuration experiment

Nucl. Fusion 58 (2018) 126026
larger, longer time is needed to accumulate necessary fast ion population for the next burst (figure 2). The azimuthal inductive electric field plays a key role in this process. The existence of this electrical field is observed in Q2D modelling [16]. The resultant Eθ × Bz force will lead to redistribution of radial equilibrium profiles, an effect that has been observed in density profile measurements [17].
4. Summary
In the advanced neutral beam driven FRC regime, clas- sical n = 1 and 2 FRC instabilities are suppressed. The good plasma and fast ion confinement properties lead to com- parable fast ion and bulk plasma pressure. In this new FRC scenario, a new macroscopically non-destructive micro-burst instability is observed experimentally in detail under some particular discharge characteristics. Most of the features of the observed micro-bursts can be explained from the theory of precession modes developed by Finn and Sudan [15]. A heuristic model that can explain the micro-burst dynamics is proposed for future investigation. In this model an inductive azimuthal electrical field plays a critical role in the micro-burst frequency down-chirping and in the radial equilibrium profile redistribution. However, this model is subject to more thor- ough theoretical examination. Hybrid MHD code or particle code simulations may be used to reproduce the bursting and frequency down-chirping characteristics, and to resolve the details of fast ion interaction with the plasma during micro- bursts. Experimentally, more accurate equilibrium diagnostics are developed for the C-2W experiment, and more flexible NBI systems are being prepared, which will allow more detailed experimental study of micro-bursts such as beam energy scans.
B.H. Deng et al
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Acknowledgments
The authors from TAE Technologies thank our shareholders for their support and trust, and all fellow TAE staff for their dedication, excellent work, and extra effort, and Hannes Lein- weber for assisting the data analysis.
ORCID iDs
B.H. Deng H. Gota
https://orcid.org/0000-0002-7025-2970 https://orcid.org/0000-0001-6475-2912
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