Comparing Current Drive Efficiencies from Empirical Models and Higher‐Fidelity Ray‐Tracing Codes for Various Heating Sources
POSTER
Abstract
The performance of confined plasmas in tokamaks is controlled by several factors including the total
current profile which is comprised of several current drives that result from plasma heating
mechanisms. These heating mechanisms include electron‐cyclotron (EC), ion‐cyclotron (IC), lower‐hybrid
(LH), helicon (HC), and neutral‐beam injection (NBI) heating [1]. Ray‐tracing codes, such as TORAY,
GENRAY, NFREYA, NUBEAM, and TORIC, have been used to accurately calculate the current drive
efficiency and deposition location for each heating mechanism. Considering the large computation
resources required for simulating many heating and current drive schemes using ray‐tracing codes while
searching for an optimum plasma scenario of high performance, the need for reduced, surrogate, or
empirical models for the current drive efficiency is necessary during the design phase [2]. In this work
we compare the current efficiencies using empirical models proposed by Tonon [3] and those calculated
in ray‐tracing codes for radio‐frequency heating mechanisms such as ECH, ICH, LHH, and HCH. The
difference between the empirical models and ray‐tracing codes varies with the heating mechanism. A
further study searches for possible adjustments needed for the empirical models to provide comparable
results to more accurate higher‐fidelity the ray‐tracing codes.
current profile which is comprised of several current drives that result from plasma heating
mechanisms. These heating mechanisms include electron‐cyclotron (EC), ion‐cyclotron (IC), lower‐hybrid
(LH), helicon (HC), and neutral‐beam injection (NBI) heating [1]. Ray‐tracing codes, such as TORAY,
GENRAY, NFREYA, NUBEAM, and TORIC, have been used to accurately calculate the current drive
efficiency and deposition location for each heating mechanism. Considering the large computation
resources required for simulating many heating and current drive schemes using ray‐tracing codes while
searching for an optimum plasma scenario of high performance, the need for reduced, surrogate, or
empirical models for the current drive efficiency is necessary during the design phase [2]. In this work
we compare the current efficiencies using empirical models proposed by Tonon [3] and those calculated
in ray‐tracing codes for radio‐frequency heating mechanisms such as ECH, ICH, LHH, and HCH. The
difference between the empirical models and ray‐tracing codes varies with the heating mechanism. A
further study searches for possible adjustments needed for the empirical models to provide comparable
results to more accurate higher‐fidelity the ray‐tracing codes.
*This work was supported by the US Department of Energy, Office of Science, Basic Energy Sciences Program under contract numbers DE‐AC05‐00OR22725 and DE‐SC0017992. Andrew Irvin was supported by an appointment to the U.S. Department of Energy's Science Undergraduate Laboratory Internships Program (SULI), sponsored by DOE and administered by the Oak Ridge Institute for Science and Education.
Publication: [1] Hassan, Ehab, et al. "Core‐Pedestal Plasma Configurations in Advanced Tokamaks." (2023).
[2] Hassan, Ehab, et al. "Searching the Plasma Geometry and Configuration Spaces for Feasible Tokamak
Design Point." (2023).
[3] Tonon, G. "Current drive efficiency requirements for an attractive steady‐state reactor." (1994).
Presenters
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Andrew M Irvin
- Oak Ridge National Laboratory