x-ray irradiation analysis based on wavelet transform in tokamak plasma

Ghanbari, Keyvan; Ghoranneviss, M.; Elahi, A. Salar; Saviz, S.

doi:10.3233/xst-140462

Cited by 11 publications

(2 citation statements)

References 19 publications

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“…In this work, the radar antenna transmits and receives continuous sinusoidal wave in time-domain and the wake velocity is extracted from the time-frequency spectrum of the reflected signal. Wavelet transform, which is frequently used in plasma characterization [9], [10], is utilized to achieve the time-frequency spectrum. The article is arranged as follows: Section II introduces the operation principle and data analysis algorithm of the proposed approach.…”

Section: Introductionmentioning

confidence: 99%

Contactless Measurement of Hypervelocity Projectile Wake Velocity Distribution

Jiang

Chen

et al. 2019

IEEE Access

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This paper presents a microwave approach to investigate the wake velocity distribution of hypervelocity projectile. The ballistic range measurement is carried out to model the transport of hypervelocity object on the ground. An X-band horn antenna sends a continuous sinusoidal wave with f c = 8.7 GHz to the hypervelocity object and detects the reflected signal. The continuous wavelet transform is utilized to obtain the Doppler frequency shift, and the wake velocity is calculated based on the theory of the Doppler effect. The validity of this experiment is confirmed by comparing the measured projectile velocity with that achieved by a laser-based velocity meter. As a contactless method, this approach does not interfere with the wake flow field. Therefore, the velocity distribution achieved in this paper exhibits better accuracy compared with that obtained from other contact approaches. INDEX TERMS Contactless, hypervelocity projectile, wake, velocity.

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Section: Introductionmentioning

confidence: 99%

Contactless Measurement of Hypervelocity Projectile Wake Velocity Distribution

Jiang

Chen

et al. 2019

IEEE Access

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“…Runaway electrons colliding with residual plasma particles and the first wall are two sources of hard X-ray radiation in tokamaks (Naghidokht et al, 2016;, 2010aGhoranneviss et al, 2010;. Although the intensity of radiation due to collisions with heavy nuclei of the first wall is higher, in both cases the dominant mechanism is bremsstrahlung (Salar Elahi & Ghoranneviss, ,c,d,e,f, 2010f, 2014Salar Elahi et al, 2009b,c;Rahimi Rad et al, 2009;Ghanbari et al, 2014Ghanbari et al, , 2016Mikaili Agah et al, 2015a,b). According to the bremsstrahlung mechanism most of the hard X-ray photons are emitted in a cone with a half-angle of 1/Y in the direction of the velocity of the emitting runaway electrons, where…”

Section: Introductionmentioning

confidence: 99%

A confident source of hard X-rays: radiation from a tokamak applicable for runaway electrons diagnosis

Kafi

Elahi

Ghoranneviss

et al. 2016

J Synchrotron Radiat

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In a tokamak with a toroidal electric field, electrons that exceed the critical velocity are freely accelerated and can reach very high energies. These so-called `runaway electrons' can cause severe damage to the vacuum vessel and are a dangerous source of hard X-rays. Here the effect of toroidal electric and magnetic field changes on the characteristics of runaway electrons is reported. A possible technique for runaways diagnosis is the detection of hard X-ray radiation; for this purpose, a scintillator (NaI) was used. Because of the high loop voltage at the beginning of a plasma, this investigation was carried out on toroidal electric field changes in the first 5 ms interval from the beginning of the plasma. In addition, the toroidal magnetic field was monitored for the whole discharge time. The results indicate that with increasing toroidal electric field the mean energy of runaway electrons rises, and also an increase in the toroidal magnetic field can result in a decrease in intensity of magnetohydrodynamic oscillations which means that for both conditions more of these high-energy electrons will be generated.

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RETRACTED ARTICLE: Review on Plasma Edge Analysis Using the Auto-Correlation and Probability Distributions of Fluctuations

2015

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We have reviewed the plasma edge fluctuations analysis over a wide range of plasma and field parameters in the IR-T1 tokamak. Fluctuation levels and spectra were measured using two arrays of Langmuir probes on the edge region. Under almost all conditions the edge plasma was turbulently unstable, with a broadband fluctuation spectrum in the drift wave range of frequencies f = 10-1000 kHz. A stable state was observed only in the very cold, low-current discharge formed at unusually high neutral filling pressure. Otherwise, the relative fluctuation level as monitored by the ion saturation current was very high while the fluctuation power spectra were roughly invariant in shape. The relative fluctuation level was always highest near the wall and decreased monotonically toward the plasma centre.

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x-ray irradiation analysis based on wavelet transform in tokamak plasma

Cited by 11 publications

References 19 publications

Contactless Measurement of Hypervelocity Projectile Wake Velocity Distribution

Contactless Measurement of Hypervelocity Projectile Wake Velocity Distribution

A confident source of hard X-rays: radiation from a tokamak applicable for runaway electrons diagnosis

RETRACTED ARTICLE: Review on Plasma Edge Analysis Using the Auto-Correlation and Probability Distributions of Fluctuations

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