The fully relativistic dielectric tensor for arbitrary wave vectors

Павлов, С. С.; Castejón, F.

doi:10.1088/1741-4326/aae6f0

Cited by 3 publications

(1 citation statement)

References 14 publications

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“…The relativistic effects are important when the thermal energy of a particle is of the order of the rest mass energy of the particle i.e., K B T ≈ m 0 c 2 . When a charged particle moves with relativistic velocity its mass increases which in turn affects all the mass-dependent quantities like the plasma frequency, cyclotron frequency and thermal velocity etc and in this way the relativistic effects appear [1][2][3].…”

Section: Introductionmentioning

confidence: 99%

Variation in the propagation characteristics of extraordinary mode with density, magnetic field and temperature in a relativistic plasma environment

Ali¹,

Khan²

2022

Phys. Scr.

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Propagation characteristics of extraordinary mode (perpendicularly propagating electromagnetic wave which is partly transverse and partly longitudinal known as X-mode) are examined in a relativistic, weakly relativis- tic and non-relativistic plasma environment for various density to magnetic field ratio ( ωpe/ωce ). The dispersion relation for X-mode is derived by using the relativistic kinetic model and employing Maxwell-Juttner distribution function. The integrals involved in the calculation are evaluated by using numerical quadrature approach. The mass dependent quantities like the cyclotron frequency and the plasma frequency will change by introducing sufficiently high temperature for which η = mc2 kB T < 1. This will effect significantly the propagation characteristics of X-mode. As the relativistic effects increase, the absorption at cyclotron frequency reduces and the dispersion characteristics of plasma vanishes. With the increase in the density or decrease in the magnetic field, the upper hybrid frequency and the right cutoff frequency shifted to a higher value, altering the propagation region.

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Section: Introductionmentioning

confidence: 99%

Variation in the propagation characteristics of extraordinary mode with density, magnetic field and temperature in a relativistic plasma environment

Ali¹,

Khan²

2022

Phys. Scr.

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Nonlinear Landau damping of electron Bernstein waves in MAST-U

Senstius,

Freethy,

Nielsen

et al. 2024

EPJ Web Conf.

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The Mega-Amp Spherical Tokamak Upgrade (MAST-U) is preparing to investigate microwave based current drive using an advanced wave coupling scheme known as O-X-B at high power. The main goal is to assert if this is an efficient method for current drive in the future fusion demonstration power plant STEP. A model for the nonlinear wave-particle interaction nonlinear Landau damping (NLD) is presented. A relativistic, kinetic and electrostatic description is used. For MAST-U, NLD could lead to heating and current drive at the upper hybrid (UH) layer or at the electron cyclotron (EC) resonance of a substantially downshifted daughter wave produced by the wave-particle interactions. It is found that the typical treatment used for nonlinear waveinteractions fails at two critical points in the vicinity of the UH layer.

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Fully-relativistic electron Bernstein wave current drive simulations in the STEP spherical tokamak

Biswas,

Freethy,

Vann

2024

Nucl. Fusion

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Electron Bernstein waves (EBWs) are theorised to efficiently drive current in spherical tokamak power plants, e.g. Spherical Tokamak for Energy Production (STEP). At high temperatures ($T_e \gtrsim 4\,$keV), relativistic effects can significantly impact wave propagation. This work presents relativistic calculations of EBW wave propagation, damping, and current drive (CD) in a conceptual STEP plasma. Kramers-Kronig relations are exploited to efficiently evaluate the fully-relativistic dispersion relation for arbitrary wave-vectors, leading to a $> \! 50$x speed-up compared to previous efforts. Current drive efficiency is calculated using both linear and quasilinear codes. Thus, for the first time, large parametric scans of fully-relativistic EBW CD simulations are performed through ray-tracing. In STEP, three main classes of rays are identified. The first class propagate deep into the core ($\rho < 0.5$), but exist only if relativistic effects are accounted for. They damp strongly at the fundamental harmonic on nearly-thermal electrons and thus drive little current. A second class of rays propagate to intermediate depths ($\rho \approx 0.3 - 0.7$) before damping at the 2nd harmonic. Their CD efficiencies are significantly altered due to relativistic changes to trajectory and polarisation. The third class of rays damp strongly far off-axis ($\rho > 0.7$), predominantly at the second harmonic. These ray trajectories are sufficiently short and ``cold'' that relativistic effects are unimportant. In linear CD simulations, the optimal launch point corresponds to this third class of rays, suggesting that non-relativistic simulations are adequate. However, quasilinear calculations indicate that, at reactor relevant powers, current drive is maximised at $\rho \approx 0.6$. This quasilinear optimal point corresponds to the second class of rays, for which relativistic propagation does matter.

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The fully relativistic dielectric tensor for arbitrary wave vectors

Cited by 3 publications

References 14 publications

Variation in the propagation characteristics of extraordinary mode with density, magnetic field and temperature in a relativistic plasma environment

Variation in the propagation characteristics of extraordinary mode with density, magnetic field and temperature in a relativistic plasma environment

Nonlinear Landau damping of electron Bernstein waves in MAST-U

Fully-relativistic electron Bernstein wave current drive simulations in the STEP spherical tokamak

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