Plasma equilibrium calculation in J-TEXT tokamak

Gao, Hua; Xu, Tao; Chen, Zhongyong; Zhuang, G.

doi:10.1088/2058-6272/aa7f26

Cited by 5 publications

(4 citation statements)

References 17 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Figures 14(d) and (h) show the radial profiles of q and magnetic shear s (s = (r/q)(dq/dr)) with and without ECRH. They are obtained by EFIT analysis [35]. There is little change in q and s in the region of r ∼ 0-0.6 and only a slight increase in the region of r/a ∼ 0.6-1 during ECRH.…”

Section: Linear Stability Analysismentioning

confidence: 84%

Observation of the electron thermal transport and temperature fluctuations for electron cyclotron resonance heated plasmas on J-TEXT

Yang¹,

Zhang²,

Ren³

et al. 2021

Nucl. Fusion

Self Cite

View full text Add to dashboard Cite

First dedicated experiments have been carried out on the J-TEXT tokamak for investigating the electron thermal transport and plasma fluctuations before and during electron cyclotron resonance heating (ECRH). The electron thermal diffusivities are calculated using the diffusive space-time evolution characteristic of the electron temperature perturbations produced by internal sawtooth collapse. It is found that the electron thermal diffusivity significantly increases as ECRH is turned on. The temperature fluctuations in the ECRH-assisted ohmic plasmas measured by the correlation electron cyclotron emission (CECE) diagnostic have a larger amplitude and broader bandwidth than that of pure ohmic plasmas. However, there is a slight change in the density fluctuations. The electron thermal diffusivities and the bandwidth of the electron temperature fluctuations decrease simultaneously as density increases in ohmic plasmas. However, the same trend is not found for ECRH-assisted ohmic plasmas with fixed ECRH power. The electron thermal diffusivities increase almost linearly with the ECRH power for the same discharge parameters, while the temperature fluctuations become broader at the same time. Linear stability analysis using the gyrokinetic electromagnetic numerical experiment code indicates that there is a turbulence transition from the mixed mode of ion temperature gradient mode and trapped electron mode (TEM) to the pure (broader) TEM when changing from pure ohmic to ECRH-assisted ohmic plasmas. It is consistent with the temperature fluctuations measured by CECE, which is sensitive to the long-wavelength modes. All these results suggest that the long-wavelength temperature fluctuations play an important role in electron thermal transport. In ECRH-assisted ohmic plasmas, electron thermal transport may become dominated by ETGs when TEMs are suppressed at high density.

show abstract

Section: Linear Stability Analysismentioning

confidence: 84%

Observation of the electron thermal transport and temperature fluctuations for electron cyclotron resonance heated plasmas on J-TEXT

Yang¹,

Zhang²,

Ren³

et al. 2021

Nucl. Fusion

Self Cite

View full text Add to dashboard Cite

show abstract

“…For the density measurement, the interferograms were generated by a 1 mm thick biprism (BK7 optical glass), then imaged onto a 16-bit chargecouple-device (CCD) camera, as shown in the inset of figure 1. By applying a 2D fast-Fourier transformation and the Abel inversion techniques on the interferograms, we could obtain the plasma density distribution [27]. The shadowgraphs of the laser plasma were directly imaged onto a 16-bit CCD camera.…”

Section: Introductionmentioning

confidence: 99%

Correlation between macroscopic plasma dynamics and electron beam parameters in a laser-plasma accelerator

Li¹,

Zhao²,

Hafz³

et al. 2018

Plasma Phys. Control. Fusion

View full text Add to dashboard Cite

Ultrafast laser-based shadowgraphic-interferometric imaging of a high-density plasma generated by intense laser-matter interactions is a key diagnostic technique providing information on the evolution and ultrafast dynamics of such a plasma state. However, shadowgraphic techniques have received modest attention in diagnosing low-density gaseous plasmas similar to those used in laser-plasma wakefield accelerators. Here, by using an ultrafast 30 fs probe laser beam, we derived a correlation between the plasma dynamics and electron beam characteristics in a laserplasma acceleration experiencing ionization injection in the plasma of a He-N 2 gas mixture. The ultrafast transverse expansion dynamics of the laser-plasma channel front tends to be faster at higher nitrogen concentrations, which leads to an increase in the divergence angle and yield (charge) of the 100−200 MeV electron beams generated in the current experiment. Computer simulation shows a distinct difference between the dynamics of the self-injection and that of the ionization-injection processes and supports the experimental observations.

show abstract

“…The ambient air pressure around the surface of laser ablated sample increases rapidly, therefore, a shockwave is generated. The reflected shockwave compresses plasma plume causing the increase in plasma temperature and electron density, so that the emission intensity is enhanced [41][42][43][44].…”

Section: Resultsmentioning

confidence: 99%

Effect of distances between lens and sample surface on laser-induced breakdown spectroscopy with spatial confinement

Jiang¹,

Shao²,

Wang³

2018

Plasma Sci. Technol.

View full text Add to dashboard Cite

Spatial confinement can significantly enhance the spectral intensity of laser-induced plasma in air. It is attributed to the compression of plasma plume by the reflected shockwave. In addition, optical emission spectroscopy of laser-induced plasma can also be affected by the distance between lens and sample surface. In order to obtain the optimized spectral intensity, the distance must be considered. In this work, spatially confined laser-induced silicon plasma by using a Nd: YAG nanosecond laser at different distances between lens and sample surface was investigated. The laser energies were 12 mJ, 16 mJ, 20 mJ, and 24 mJ. All experiments were carried out in an atmospheric environment. The results indicated that the intensity of Si (I) 390.55 nm line firstly rose and then dropped with the increase of lens-to-sample distance. Moreover, the spectral peak intensity with spatial confinement was higher than that without spatial confinement. The enhancement ratio was approximately 2 when laser energy was 24 mJ.

show abstract

Plasma equilibrium calculation in J-TEXT tokamak

Cited by 5 publications

References 17 publications

Observation of the electron thermal transport and temperature fluctuations for electron cyclotron resonance heated plasmas on J-TEXT

Observation of the electron thermal transport and temperature fluctuations for electron cyclotron resonance heated plasmas on J-TEXT

Correlation between macroscopic plasma dynamics and electron beam parameters in a laser-plasma accelerator

Effect of distances between lens and sample surface on laser-induced breakdown spectroscopy with spatial confinement

Contact Info

Product

Resources

About