The generation of energetic tails in the electron distribution function is intrinsic to lower‐hybrid (LH) heating and current drive in weakly collisional magnetically confined plasma. The effects of these deformations on the RF deposition profile have previously been examined within the ray approximation [1, 2]. Recently, the calculation of full‐wave propagation of LH waves in a thermal plasma [3] has been accomplished using an adaptation of the TORIC [4] code. Here, initial results are presented from TORIC simulations of LH propagation in a toroidal plasma with non‐thermal electrons. The required efficient computation of the hot plasma dielectric tensor is accomplished using a technique previously demonstrated in full‐wave simulations of ICRF propagation in plasma with non‐thermal ions [5].

/pdf/full-wave-simulations-of-lh-wave-propagation-in-toroidal-feczlpst27.pdf

Full‐wave Simulations of LH wave propagation in toroidal plasma with non‐Maxwellian electron distributions

A current drive package that evaluates the current driven by fast magnetosonic waves in arbitrary flux geometry directly from the wave-induced quasilinear flux and a Green’s function for the current has been developed. An expression for the quasilinear flux has been derived which accounts for coupling between modes in the spectrum of waves launched from the antenna. The field amplitudes are calculated from a toroidal full wave ICRF code, and the current response function, χ, also known as the Spitzer function, is determined with a bounce averaged Fokker-Planck code. Both codes have been modified to use a self consistent MHD numerical equilibria obtained by solving the GradShafranov equation. To model the effects of a trapped particle population, the bounce averaged equations for current and power are used, and the bounce averaged flux is calculated. The computer model is benchmarked against the homogeneous equations for a high aspect ratio case in which the expected agreement is confirmed. Results from cases for TFTR and NSTX are contrasted with the predictions of an analytic parameterization of current drive for circular equilibria.

Fast wave current drive modeling in Tokamaks

In advanced toroidal devices, plasma shaping can have a significant effect on quantities of interest, including the radio frequency (RF) deposited power and current. Most 2D RF modeling codes use a parameterization of current drive efficiencies to calculate fast wave driven currents. This parameterization is derived from a ray-tracing model in a low-beta model equilibrium. There are difficulties in applying it to a spectrum of waves, and it cannot account for multiple resonances and coherency effects between the electrons and the waves. By evaluating a formulation of the quasilinear diffusion coefficient in an arbitrary inhomogenous geometry with the fields from a full wave code, we address the effects of wave spectra, plasma inhomogeneity, and plasma profile on the evaluation of current deposition profiles. Current profiles are calculated directly from the quasilinear diffusion using the adjoint formulation, with the magnetic equilibrium specified consistently in both the adjoint routine and the full wave code. Results are benchmarked by comparing a power deposition calculation from conductivity to one from the quasilinear expression. RF driven current profiles for various devices, including tokamaks with different aspect ratios, will be presented.

Current deposition profiles in advanced geometries

Two‐dimensional RF modeling codes use a parameterization (1) of current drive efficiencies to calculate fast wave driven currents. This parameterization assumes a uniform quasi‐linear diffusion coefficient and requires a priori knowledge of the wave polarizations. These difficulties may be avoided by a direct calculation of the quasilinear diffusion coefficient from the Kennel‐Englemann form with the field polarizations calculated by the full wave code, FISIC (2). Current profiles are calculated using the adjoint formulation (3). Comparisons between the two formulations are presented.

Direct calculation of current drive efficiency in FISIC code

At the power levels required for signicant heating and current drive in magnetically-con ned toroidal plasma, modi cation of the particle distribution function from a Maxwellian shape is likely [T.H. Stix, Nucl. Fusion, 15:737 1975], with consequent changes in wave propagation and in the location and amount of absorption. In order to study these e ects computationally, the nite-Larmor-radius, full-wave, hot-plasma toroidal simulation code, TORIC [M. Brambilla. Plasma Phys. Controlled Fusion, 41:1, 1999], has been extended to allow the prescription of arbitrary velocity distributions of the form ƒ (ν||, ν⊥, Ψ, θ). For H minority heating of a D-H plasma with anisotropic Maxwellian H distributions, the fractional H absorption varies signi cantly with changes in parallel temperature but is essentially independent of perpendicular temperature.

/pdf/full-wave-simulations-of-icrf-heating-in-toroidal-plasma-54b1k1on5b.pdf

Full-wave Simulations of ICRF Heating in Toroidal Plasma with Non-Maxwellian Distribution Functions in the FLR Limit

Handle everyday research tasks with reliable, citation-backed results

Your personal Research Agent to handle research tasks with citation-backed results

Popular Tasks used by Researchers

How can I help with your research?

Meet SciSpace

Get more enhanced response by uploading the PDFs you want me to reference.

No relevant PDFs in your library

SciSpace is the AI research assistant for academics. Run systematic literature reviews on 280M+ papers, and write papers with cited sources. Trusted by 1M+ students, PhDs & researchers.

SciSpace | AI for Research

Analyze PDFs

Code & Manuscripts

Funding & Grants

Literature & Patents

Medical & Clinical Data

Systematic Review

Visualize & Present

Web & Data

Build a Google Scholar-like website for your research.

Build a website

Create charts and images for your research

Create a Chart

Write a paper for submission to a journal

Draft a manuscript

Patent Search

Design eye-catching scientific posters in minutes.

Scientific Poster Generation

Systematic Literature Review

One task is running at the moment. Your messages will be shown right after.

Drag and drop or click here to browse

Loved by <highlight>1 million+</highlight> researchers

Extract a list of specific topics and their sources from unstructured text

Topics

Compare and analyze relevant papers that matches with your search

Papers

Get insights from PDFs and bookmarked papers from your library

My library

Recent searches

Try searching for:

Catch AI-generated content in scholarly and non-scholarly content

{ai} Detector

Ai Writer

Get PDF Summaries, highlighted text explanations 

Chat with PDF

Effortlessly create in-text citations and bibliographies in APA and 2,500 other formats

Citation generator

Get explanations, summaries, and answers on academic papers

Ease up your research workflow with {scispace}'s cohort of exciting AI tools

Elevate your academic writing skills and convey your ideas the way you want

Paraphraser

Explore our range of reading and writing tools

Your file is being prepared and should be ready in a few minutes. If it's a large file, it might take a bit longer. You can close this window, and we'll email you the file when it's done.

You have reached a maximum limit of <strong>{limit}</strong> columns in the table. Remove at least <strong>1</strong> column to add or create another one.

J. C. Wright

Author Tools

Chat about Author

Papers

Direct calculation of current drive efficiency in FISIC code

Current deposition profiles in advanced geometries

Full-wave Simulations of ICRF Heating in Toroidal Plasma with Non-Maxwellian Distribution Functions in the FLR Limit