Inversion technique to obtain local rotation velocity and ion temperature from line-integrated measurements for elongated tokamak plasma

2012 ◽  
Vol 83 (10) ◽  
pp. 10D717 ◽  
Author(s):  
Y. J. Shi ◽  
S. G. Lee ◽  
K. W. Hill ◽  
M. Bitter
Keyword(s):  
Rotation Velocity ◽  
Tokamak Plasma ◽  
Ion Temperature ◽  
Local Rotation ◽  
Inversion Technique

scholarly journals Poloidal Rotation and Edge Ion Temperature Measurements Using Spectroscopy Diagnostic on Aditya-U Tokamak

Atoms ◽  
2019 ◽  
Vol 7 (3) ◽  
pp. 93
Author(s):  
Gaurav Shukla ◽  
Malay B. Chowdhuri ◽  
Kajal Shah ◽  
Nandini Yadava ◽  
Ranjana Manchanda ◽  
...  
Keyword(s):  
High Resolution ◽  
Line Emission ◽  
Rotation Velocity ◽  
Spectral Lines ◽  
Tokamak Plasma ◽  
Vacuum Vessel ◽  
Ion Temperature ◽  
Minor Radius ◽  
Impurity Ion ◽  
Poloidal Rotation

The impurity ion poloidal rotation and ion temperature from the Aditya-U tokamak plasma have been measured using a high-resolution spectroscopic diagnostic. It comprises of a high resolution, 1 m, f/8.7, Czerny-Turner configuration spectrometer along with charge coupled device (CCD) detector. The system monitors the spectral line emission of C2+ impurity ions at 464.74 nm from the top port of the Aditya-U vacuum vessel with the lines of sight covering the plasma minor radius from r = 11.55 cm to 21.55 cm. The impurity ion poloidal rotation velocity and temperature have been estimated using the Doppler shift and Doppler broadening of the spectral lines respectively. The maximum poloidal rotation at a radial location of 21.55 cm in the edge of the plasma during the plasma current flat top was observed to be ~4 km/s for the analyzed discharges and the ion temperatures measured in the edge were in the range of 32–40 eV.

The ITB dynamics controlled by internal kink modes on HL-2A tokamak

2021 ◽  
Author(s):  
Xiaoxue He ◽  
Longwen Yan ◽  
Deliang Yu ◽  
Wei Chen ◽  
Liming Yu ◽  
...  
Keyword(s):  
High Performance ◽  
Fusion Reactor ◽  
Rotation Velocity ◽  
Plasma Current ◽  
Ion Temperature ◽  
Lower Plasma ◽  
Transport Barriers ◽  
Internal Transport Barriers ◽  
Foot Position ◽  
Internal Transport

Abstract The active control of internal transport barriers (ITBs) is an important issue to achieve high performance plasma in a fusion reactor. A critical challenge of ITB control is to increase the ITB position. The ITBs with internal kink modes (IKMs), such as fishbone instability and long-live mode (LLM) with mode number of m/n = 1/1 are frequently observed on HL-2A tokamak in neutral beam heated discharges. The correlation of fishbone instability/LLM with ITBs is analyzed in order to extend the ITB radius. It has been revealed that fishbone instability and LLM are often excited after the ITB formation. Therefore, fishbone instability and LLM play no role in triggering ITBs on HL-2A tokamak. On the other hand, they may slow down the outward radial expansion and then shrink the foot position of ITB, and damp the gradient growth of ion temperature and rotation velocity. Since the perturbation of LLM is weaker than that of fishbone instability, the shrinking effect of ITB foot and braking effect on gradient growth are slighter than those of fishbone instability. Compared with the LLM, fishbone instability routinely appears in plasmas with lower density, higher heating power and lower plasma current. In addition, large ITBs without IKMs are also discussed on HL-2A tokamak. The large ITB is the largest one, the fishbone ITB is the strongest one and the LLM ITB is the widest one in three ITBs, where the ‘large’, ‘strong’ and ‘wide’ qualifications correspond to ITB position ρITB, the normalized temperature gradient R/LT, and its width W/a. Therefore, the large ITB position may be obtained if the IKMs are effectively controlled in a tokamak.

Impurity ion temperature and toroidal rotation velocity in JET from high‐resolution x‐ray and XUV spectroscopy

1988 ◽  
Vol 64 (7) ◽  
pp. 3345-3352 ◽  
Author(s):  
M. Mattioli ◽  
J. Ramette ◽  
B. Saoutic ◽  
B. Denne ◽  
E. Källne ◽  
...  
Keyword(s):  
High Resolution ◽  
Rotation Velocity ◽  
Ion Temperature ◽  
X Ray ◽  
Toroidal Rotation ◽  
Xuv Spectroscopy ◽  
Impurity Ion

scholarly journals Transition to subcritical turbulence in a tokamak plasma

2016 ◽  
Vol 82 (6) ◽  
Author(s):  
F. van Wyk ◽  
E. G. Highcock ◽  
A. A. Schekochihin ◽  
C. M. Roach ◽  
A. R. Field ◽  
...  
Keyword(s):  
Temperature Gradient ◽  
Initial Perturbation ◽  
Outer Core ◽  
Transition To Turbulence ◽  
Tokamak Plasma ◽  
Ion Temperature ◽  
Flow Shear ◽  
Ion Temperature Gradient ◽  
Stability Threshold ◽  
Accretion Flows

Tokamak turbulence, driven by the ion-temperature gradient and occurring in the presence of flow shear, is investigated by means of local, ion-scale, electrostatic gyrokinetic simulations (with both kinetic ions and electrons) of the conditions in the outer core of the Mega-Ampere Spherical Tokamak (MAST). A parameter scan in the local values of the ion-temperature gradient and flow shear is performed. It is demonstrated that the experimentally observed state is near the stability threshold and that this stability threshold is nonlinear: sheared turbulence is subcritical, i.e. the system is formally stable to small perturbations, but, given a large enough initial perturbation, it transitions to a turbulent state. A scenario for such a transition is proposed and supported by numerical results: close to threshold, the nonlinear saturated state and the associated anomalous heat transport are dominated by long-lived coherent structures, which drift across the domain, have finite amplitudes, but are not volume filling; as the system is taken away from the threshold into the more unstable regime, the number of these structures increases until they overlap and a more conventional chaotic state emerges. Whereas this appears to represent a new scenario for transition to turbulence in tokamak plasmas, it is reminiscent of the behaviour of other subcritically turbulent systems, e.g. pipe flows and Keplerian magnetorotational accretion flows.

Characteristic peaked profiles of ion temperature and toroidal rotation velocity in JT-60 hot ion modes

1993 ◽  
Vol 33 (2) ◽  
pp. 251-261 ◽  
Author(s):  
Y Koide ◽  
S Ishida ◽  
A Sakasai ◽  
H Shirai ◽  
T Hirayama ◽  
...  
Keyword(s):  
Rotation Velocity ◽  
Ion Temperature ◽  
Toroidal Rotation
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