Radiated energy fraction of SPI-induced disruptions at ASDEX Upgrade

Kód výsledku v IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F61389021%3A_____%2F25%3A00648043" target="_blank" >RIV/61389021:_____/25:00648043 - isvavai.cz</a>

Výsledek na webu

<a href="https://iopscience.iop.org/article/10.1088/1741-4326/adcbc0" target="_blank" >https://iopscience.iop.org/article/10.1088/1741-4326/adcbc0</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1088/1741-4326/adcbc0" target="_blank" >10.1088/1741-4326/adcbc0</a>

Jazyk výsledku

angličtina

Název v původním jazyce

Radiated energy fraction of SPI-induced disruptions at ASDEX Upgrade

Popis výsledku v původním jazyce

Future large tokamaks will operate at high plasma currents and high stored plasma energies. To ensure machine protection in case of a sudden loss of plasma confinement (major disruption), a large fraction of the magnetic and thermal energy must be radiated to reduce thermal loads. The disruption mitigation system for ITER is based on massive material injection in the form of shattered pellet injection (SPI). To support ITER, a versatile SPI system was installed at the tokamak ASDEX Upgrade (AUG). The AUG SPI features three independent pellet generation cells and guide tubes, and each was equipped with different shatter heads for the 2022 experimental campaign. We dedicated over 200 plasma discharges to the study of SPI plasma termination, and in this manuscript report on the results of bolometry (total radiation) analysis. We found, that the amount of neon inside the pellets is the dominant factor determining the radiated energy fraction ( f rad ). Large and fast fragments, produced by the 12.5 ∘ rectangular shatter head, lead to somewhat higher values of f rad compared to the 25° circular or rectangular heads. This effect is strongest for neon content of ≲ 3 × 10 20 neon atoms ( f neon ≲ 1.25 % neon) injected, where a lower normal velocity component (larger fragments) seems slightly beneficial. While full-sized, 8 mm diameter, 100% deuterium ( D 2 ) pellets lead to a disruption, the 4 mm or shortened 8 mm pellets of 100% D 2 did not. The disruption threshold for 100% D 2 is found to be around 1 × 10 22 deuterium molecules inside the pellet. While the radiated energy fraction of non-disruptive SPI is below 20%, this is increased to 40% during the thermal quench and vertical displacement event phase of the disruptive injections. For deuterium-neon-mix pellets, f radvalues of ⩽ 90 % are observed, and the curve saturates around 80% already for 10% neon mixed into the 8 mm pellets ( 2 × 10 21 neon atoms).

Název v anglickém jazyce

Radiated energy fraction of SPI-induced disruptions at ASDEX Upgrade

Popis výsledku anglicky

Future large tokamaks will operate at high plasma currents and high stored plasma energies. To ensure machine protection in case of a sudden loss of plasma confinement (major disruption), a large fraction of the magnetic and thermal energy must be radiated to reduce thermal loads. The disruption mitigation system for ITER is based on massive material injection in the form of shattered pellet injection (SPI). To support ITER, a versatile SPI system was installed at the tokamak ASDEX Upgrade (AUG). The AUG SPI features three independent pellet generation cells and guide tubes, and each was equipped with different shatter heads for the 2022 experimental campaign. We dedicated over 200 plasma discharges to the study of SPI plasma termination, and in this manuscript report on the results of bolometry (total radiation) analysis. We found, that the amount of neon inside the pellets is the dominant factor determining the radiated energy fraction ( f rad ). Large and fast fragments, produced by the 12.5 ∘ rectangular shatter head, lead to somewhat higher values of f rad compared to the 25° circular or rectangular heads. This effect is strongest for neon content of ≲ 3 × 10 20 neon atoms ( f neon ≲ 1.25 % neon) injected, where a lower normal velocity component (larger fragments) seems slightly beneficial. While full-sized, 8 mm diameter, 100% deuterium ( D 2 ) pellets lead to a disruption, the 4 mm or shortened 8 mm pellets of 100% D 2 did not. The disruption threshold for 100% D 2 is found to be around 1 × 10 22 deuterium molecules inside the pellet. While the radiated energy fraction of non-disruptive SPI is below 20%, this is increased to 40% during the thermal quench and vertical displacement event phase of the disruptive injections. For deuterium-neon-mix pellets, f radvalues of ⩽ 90 % are observed, and the curve saturates around 80% already for 10% neon mixed into the 8 mm pellets ( 2 × 10 21 neon atoms).

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

2025

Kód důvěrnosti údajů

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

Název periodika

Nuclear Fusion

ISSN

0029-5515

e-ISSN

1741-4326

Svazek periodika

65

Číslo periodika v rámci svazku

5

Stát vydavatele periodika

US - Spojené státy americké

Počet stran výsledku

15

Strana od-do

056036

Kód UT WoS článku

001476013700001

EID výsledku v databázi Scopus

2-s2.0-105003695502