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Title: Stability analysis of runaway-driven waves in a tokamak

Publication Date:
Sponsoring Org.:
OSTI Identifier:
Grant/Contract Number:
DEFG02-04ER54742; ITER-CT-12-4300000273
Resource Type:
Journal Article: Publisher's Accepted Manuscript
Journal Name:
Nuclear Fusion
Additional Journal Information:
Journal Volume: 55; Journal Issue: 4; Related Information: CHORUS Timestamp: 2017-01-25 22:29:00; Journal ID: ISSN 0029-5515
IOP Publishing
Country of Publication:

Citation Formats

Aleynikov, Pavel, and Breizman, Boris. Stability analysis of runaway-driven waves in a tokamak. IAEA: N. p., 2015. Web. doi:10.1088/0029-5515/55/4/043014.
Aleynikov, Pavel, & Breizman, Boris. Stability analysis of runaway-driven waves in a tokamak. IAEA. doi:10.1088/0029-5515/55/4/043014.
Aleynikov, Pavel, and Breizman, Boris. 2015. "Stability analysis of runaway-driven waves in a tokamak". IAEA. doi:10.1088/0029-5515/55/4/043014.
title = {Stability analysis of runaway-driven waves in a tokamak},
author = {Aleynikov, Pavel and Breizman, Boris},
abstractNote = {},
doi = {10.1088/0029-5515/55/4/043014},
journal = {Nuclear Fusion},
number = 4,
volume = 55,
place = {IAEA},
year = 2015,
month = 3

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record at 10.1088/0029-5515/55/4/043014

Citation Metrics:
Cited by: 4works
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  • The tokamak shaping effects on the toroidal branch of the ion-temperature-gradient-driven mode in the long wavelength limit ([ital k][sup 2][sub [chi]][rho][sup 2][sub [ital i]][much lt][epsilon][sup 1/2][sub [ital T]]) are studied. A model equilibrium with noncircular cross section is employed, where elongation, Shafranov shift, and triangularity are all taken into account. It is shown that each Fourier term in the expansion of the equilibrium magnetic field is associated with a new branch of the dispersion relation.
  • The anisotropy of the distribution of runaway electrons in velocity space has been studied experimentally in the TM-3 tokamak during the instability of the runaway-electron beam (the ''fan'' instability). The anisotropy is estimated by comparing the experimental and calculated x-ray spectra (10 keV
  • The role of runaway electrons in current ramping by lower hybrid waves is discussed. The back emf induced by current ramping using lower hybrid waves produces runaway electrons at such a rate that the rate of change of the current carried by runaways can completely compensate the RF current ramp rate if runaways are well-confined. However, runaway electrons can also destabilize the oblique plasma waves due to their anisotropy. The resulting turbulence can greatly reduce the runaway production rate, enabling the current ramping rate to exceed the above limit.
  • In this paper, the secular full-orbit simulations of runaway electrons with synchrotron radiation in tokamak fields are carried out using a relativistic volume-preserving algorithm. Detailed phase-space behaviors of runaway electrons are investigated in different dynamical timescales spanning 11 orders. In the small timescale, i.e., the characteristic timescale imposed by Lorentz force, the severely deformed helical trajectory of energetic runaway electron is witnessed. A qualitative analysis of the neoclassical scattering, a kind of collisionless pitch-angle scattering phenomena, is provided when considering the coupling between the rotation of momentum vector and the background magnetic field. In large timescale up to 1 s,more » it is found that the initial condition of runaway electrons in phase space globally influences the pitch-angle scattering, the momentum evolution, and the loss-gain ratio of runaway energy evidently. However, the initial value has little impact on the synchrotron energy limit. It is also discovered that the parameters of tokamak device, such as the toroidal magnetic field, the loop voltage, the safety factor profile, and the major radius, can modify the synchrotron energy limit and the strength of neoclassical scattering. The maximum runaway energy is also proved to be lower than the synchrotron limit when the magnetic field ripple is considered.« less
  • A theory is derived for the excitation of a current by lower hybrid waves in a nonuniform plasma. The effect of the rf energy dissipated in the plasma and of the rf current which is excited on the plasma energy balance is taken into account. The results of a numerical simulation agree satisfactorily with experiments on the excitation of an rf current in the JFT-2 device. It is shown that lower hybrid waves can be used to excite a steady-state current in a tokamak reactor.