Effects on characteristics of plasma disruption mitigation using shattered pellet injection with different shatter tubes on EAST
Plasma disruptions present considerable risks to tokamak devices, necessitating the implementation of advanced mitigation techniques such as shattered pellet injection (SPI). This study examines the influence of various shatter tube designs on disruption mitigation characteristics in EAST. The stand...
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| Main Authors: | , , , , , , , , , , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
IOP Publishing
2025-01-01
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| Series: | Nuclear Fusion |
| Subjects: | |
| Online Access: | https://doi.org/10.1088/1741-4326/adeb9c |
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| Summary: | Plasma disruptions present considerable risks to tokamak devices, necessitating the implementation of advanced mitigation techniques such as shattered pellet injection (SPI). This study examines the influence of various shatter tube designs on disruption mitigation characteristics in EAST. The standard 20°-bend shatter tube was replaced with a horizontal straight tube to develop an insufficiently SPI (ISPI) system, producing larger and off-axis injected fragments without velocity reduction for comparative analysis with conventional SPI. It was found that after impurity injection, the n = 1 mode in the toroidal signals grows regardless of whether a magnetohydrodynamic (MHD) mode was present in the plasma before injection. Diagnostic assessments indicate that ISPI results in a pre-thermal quench (pre-TQ) duration about 1.5 times longer than SPI attributed to reduced impurity assimilation and a current quench duration 0.83 times shorter than SPI attributed to the fast I _p dissipation via halo current caused by the cold vertical displacement event (VDE). Although ISPI facilitates a slightly more uniform poloidal radiation distribution during the TQ phase, it is associated with weaker mitigation of halo currents, with a mitigation rate of 27.3% compared to SPI’s 64.7%. These findings provide critical insights for optimizing ITER’s SPI strategy by balancing radiation homogeneity, electromagnetic load management, and MHD stability. |
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| ISSN: | 0029-5515 |