Systematic errors in tokamak magnetic equilibrium reconstruction: A study of EFIT++ at tokamak COMPASS

Kód výsledku v IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F61389021%3A_____%2F19%3A00531252" target="_blank" >RIV/61389021:_____/19:00531252 - isvavai.cz</a>

Nalezeny alternativní kódy

RIV/68407700:21340/19:00336431

Výsledek na webu

<a href="https://iopscience.iop.org/article/10.1088/1748-0221/14/11/C11020" target="_blank" >https://iopscience.iop.org/article/10.1088/1748-0221/14/11/C11020</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1088/1748-0221/14/11/C11020" target="_blank" >10.1088/1748-0221/14/11/C11020</a>

Jazyk výsledku

angličtina

Název v původním jazyce

Systematic errors in tokamak magnetic equilibrium reconstruction: A study of EFIT++ at tokamak COMPASS

Popis výsledku v původním jazyce

Uncertainties and errors in magnetic equilibrium reconstructions are a wide-spread problem in interpreting experimental data measured in the tokamak edge. This study demonstrates errors in EFIT++ reconstructions performed on the COMPASS tokamak by comparing the outer midplane separatrix position to the Velocity Shear Layer (VSL) position. The VSL is detected as the plasma potential peak measured by a reciprocating ball-pen probe. A subsequent statistical analysis of nearly 400 discharges shows a strong systematic trend in the reconstructed separatrix position relative to the VSL, where the primary factors are plasma triangularity and the magnetic axis radial position. This dependency is significantly reduced after the measuring coils positions as recorded in EFIT input are optimised to provide a closer match between the „synthetic“ coil signal calculated by the Biot-Savart law in a vacuum discharge and the actual coil signal. In conclusion, we suggest that applying this optimisation may lead to more accurate and reliable reconstructions of the COMPASS equilibrium, which would have a positive impact on the accuracy of measurement analysis performed in the edge plasma.

Název v anglickém jazyce

Systematic errors in tokamak magnetic equilibrium reconstruction: A study of EFIT++ at tokamak COMPASS

Popis výsledku anglicky

Uncertainties and errors in magnetic equilibrium reconstructions are a wide-spread problem in interpreting experimental data measured in the tokamak edge. This study demonstrates errors in EFIT++ reconstructions performed on the COMPASS tokamak by comparing the outer midplane separatrix position to the Velocity Shear Layer (VSL) position. The VSL is detected as the plasma potential peak measured by a reciprocating ball-pen probe. A subsequent statistical analysis of nearly 400 discharges shows a strong systematic trend in the reconstructed separatrix position relative to the VSL, where the primary factors are plasma triangularity and the magnetic axis radial position. This dependency is significantly reduced after the measuring coils positions as recorded in EFIT input are optimised to provide a closer match between the „synthetic“ coil signal calculated by the Biot-Savart law in a vacuum discharge and the actual coil signal. In conclusion, we suggest that applying this optimisation may lead to more accurate and reliable reconstructions of the COMPASS equilibrium, which would have a positive impact on the accuracy of measurement analysis performed in the edge plasma.

Druh

J_imp - Článek v periodiku v databázi Web of Science

CEP obor

—

OECD FORD obor

10305 - Fluids and plasma physics (including surface physics)

Projekt

—

Návaznosti

I - Institucionalni podpora na dlouhodoby koncepcni rozvoj vyzkumne organizace

Rok uplatnění

2019

Kód důvěrnosti údajů

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

Název periodika

Journal of Instrumentation

ISSN

1748-0221

e-ISSN

—

Svazek periodika

14

Číslo periodika v rámci svazku

11

Stát vydavatele periodika

GB - Spojené království Velké Británie a Severního Irska

Počet stran výsledku

7

Strana od-do

C11020

Kód UT WoS článku

000507588300020

EID výsledku v databázi Scopus

2-s2.0-85082806934