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UKAEA-CCFE-PR(26)4222025
Dedicated experiments were conducted on Alfvénic instabilities in the ion sub-cyclotron frequency range excited by energetic beam ions in the MAST-Upgrade tokamak. Losses of the beam ions associated with plasma instabilities were measured with a scintillator-type fast ion lost detector (FILD), which provided a 2D image of the losses as functions o…
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UKAEA-CCFE-CP(26)342024
The MAST-U spherical tokamak (ST) is equipped with on-axis and off-axis neutral beam injectors (NBI), external sources of super-Alfvénic fast ions that provide opportunities for studying a wide range of phenomena relevant to the physics of alpha-particles in future burning plasma devices such as STEP or ITER. High performance of MAST-U plasmas rel…
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UKAEA-CCFE-CP(26)322024
Tikhonov regularization has so far been the method par excellence applied to Fast Ion Loss Detector (FILD) [1] measurements to obtain an accurate fast ion velocity distribution [2]. To address two major drawbacks of Tikhonov regularization, the computational expense and the critical reliance on the optimal value of a hyperparameter, iterative algor…
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UKAEA-CCFE-PR(25)3932024
A Fast-Ion Loss Detector (FILD) was installed for the first time at the MAST-U spherical tokamak during its upgrade in 2021. A CMOS camera was installed in the MAST-U FILD acquisition system to provide high spatial resolution (1.1 MPx) to infer the velocity space of the fast-ion losses. This camera allows up to 3.5 kHz ac…
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UKAEA-CCFE-PR(24)2152024
The first observations and classification of sub-cyclotron frequency range Alfvén eigenmodes (AEs) are presented for the MAST Upgrade tokamak. Sets of observed eigenmodes are separated by approximately 200 kHz. We observe a low frequency separation of ~10 kHz within the set, and the toroidal mode number n increases with frequency sequentially. …
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UKAEA-CCFE-CP(25)282023
MAST-U is equipped with on-axis and off-axis neutral beam injectors (NBI), external sources of super-Alfvénic fast-ions that provide opportunities for studying a wide range of phenomena relevant to the physics of alpha-particles in burning plasmas. Clear evidence of fast-ion redistribution and loss due to sawteeth (ST), fishbones (FB), long-liv…
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UKAEA-CCFE-CP(24)112023
The first scintillator-based Fast-Ion Loss Detector (FILD) was installed in MAST-U as part of its main upgrade and it was commissioned during the first experimental campaign. FILD works as a magnetic spectrometer, directly measuring neutral beam injection (NBI) fast-ion losses using a scintillator plate that emits light when fast ions impinge on it…
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UKAEA-CCFE-PR(23)162023
Observations of enhanced fast-ion losses during edge localized modes (ELMs) have been reported in the ASDEX Upgrade tokamak, revealing losses above the injection energy. This suggests that fast ions can be accelerated and lost by the ELMs. Recent analysis delves into the analysis of the ELM-induced losses, suggesting that the fast ions are los…
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UKAEA-CCFE-CP(23)442022
Due to their relatively higher Vbeam/VAlvén ratio, spherical tokamaks are ideal to investigate high-frequency modes such as Compressional Alfvén Eigenmodes (CAEs) and Global Alfvén Eigenmodes (GAEs), and so they have been previously studied in MAST [1, 2]. Besides, the recently installed scintillator-based Fast-Ion Loss …
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