The response of a fast scintillator screen (YAP:Ce) to low energy ions (0-40 keV) and its use to detect fast-ion-loss in stellarator TJ-II

Martínez, M.; Zurro, B.; Baciero, A.; Jiménez-Rey, D.; Tribaldos, V.; Malo, M.; Crespo, M.T.; Munoz, D. Camarero

doi:10.1063/1.4959944

Cited by 1 publication

(2 citation statements)

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“…The LP was operated, for the first time, in the energy range from 1 to 40 keV as a multichannel fast‐ion energy spectrometer (with a maximum resolution in energy of 10 eV and maximum temporal resolution time of 1 ns). This was performed using the correlation between pulse height and the emission amplitude of the YAP:Ce, where the signal is acquired using a system that can be operated up to 1 GHz (ADQ14DC‐2C‐USB). This LP set‐up avoids signal pile‐up effects because of its high acquisition frequency and the fast decay time of the YAP:Ce.…”

Section: Experiments and Lp Set‐upmentioning

confidence: 99%

“…However, there exist fusion‐relevant plasma phenomena (such as ELM‐like instabilities) with shorter timescales (<1 ms) that could affect ion confinement. In order to explore this, the LP has been upgraded . It is now operated with a faster phosphor, YAP:Ce (Yttrium Aluminium Perovskite doped with cerium, decay time = 27 ns) and higher‐speed electronics and a data acquisition system (up to 1 GHz, previously 1 MHz).…”

Section: Introductionmentioning

confidence: 99%

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Discrete fast‐ion detection with energy discrimination in plasmas having edge‐localized mode‐like instabilities in the stellarator TJ‐II

Martínez

Zurro²,

Baciero³

et al. 2018

Contributions to Plasma Physics

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The existence of a population of ions, with energies well above the corresponding thermal values, in plasmas heated by neutral beam injection (NBI) in the stellarator TJ-II and in other magnetically confined plasmas devices is well known. Moreover, during the NBI phase of the TJ-II, edge-localized mode-like (ELM-like) instabilities often appear. This work studies the relationship between fast ions escaping from TJ-II plasmas and such ELM-like events. For this, an ion luminescent probe (LP), operated with a fast scintillator (decay time = 27 ns) and high-speed conditioning electronics (100 MHz), is used to measure, without pile-up effects, the energy distribution of suprathermal ions across the energy range, from 1 to 30 keV. It is found that the LP detects suprathermal ion populations that can be related to ELM-like events whose temperatures oscillate between 0.5 and 3 keV and that can be distinguished in a spectrogram of the LP response as an increase in frequencies from 15 to 150 kHz. Finally, observations of substructures within ELM-likes events, consisting of bursts of ions, with times between 5 and 15 μs are also reported. Such substructures have been observed previously in both tokamaks and stellarators in ion saturation current, high-speed camera images, etc. However, understanding the fast-ion component can provide new and relevant information about the behaviour of ions.

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Section: Experiments and Lp Set‐upmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%