Quasimode decay of a lower-hybrid wave in a two-electron-temperature plasma

1996 ◽  
Vol 56 (2) ◽  
pp. 237-249
Author(s):  
A. Sudarshan ◽  
S. K. Sharma
Keyword(s):  
Growth Rate ◽  
Electron Temperature ◽  
Decay Channel ◽  
Lower Hybrid ◽  
Hybrid Wave ◽  
Lower Hybrid Wave ◽  
Temperature Plasma ◽  
Parametric Decay ◽  
Cylindrical Plasma ◽  
Ion Cyclotron

We study the quasimode decay of a lower-hybrid wave and a damped ion cyclotron wave in a plasma having two kinds of electrons. This decay channel is also investigated for a cylindrical plasma. The behaviour of the threshold and growth rate with variations in Tn/Tc and non/noc are studied, and a comparison is made with previous results. Our results show that the growth rate and the threshold for the onset of parametric decay are influenced by the presence of the second electron species.

Parametric decay instability of an upper-hybrid wave in a two-temperature plasma

1994 ◽  
Vol 51 (2) ◽  
pp. 193-200 ◽  
Author(s):  
S. Konar ◽  
V. Rai
Keyword(s):  
Growth Rate ◽  
Electron Temperature ◽  
Density Ratio ◽  
Low Frequency ◽  
Lower Hybrid ◽  
Hot Electron ◽  
Hybrid Wave ◽  
Temperature Plasma ◽  
Band Frequency ◽  
Parametric Decay

Parametric decay of an upper-hybrid pump into another upper-hybrid wave and a low-frequency lower-hybrid mode is considered in a two-electron temperature plasma. Expressions for the nonlinear dispersion relation and growth rate are obtained. It is found that the growth rate is quite sensitive to the hot-electron temperature and the density ratio of the hot and the cold components only when the side-band frequency is close to the second or third harmonic of the cyclotron frequency. The relevance of our investigation to Q machines and the ELMO bumpy torus is pointed out.

Parametric decay in a two-electron-temperature plasma

1990 ◽  
Vol 43 (3) ◽  
pp. 451-456
Author(s):  
S. Guha ◽  
Meenu Asthana
Keyword(s):  
Growth Rate ◽  
Dispersion Relation ◽  
Electron Temperature ◽  
Pump Wave ◽  
Nonlinear Dispersion ◽  
Hybrid Wave ◽  
Temperature Plasma ◽  
Parametric Decay ◽  
Electromagnetic Pump ◽  
Nonlinear Dispersion Relation

Nonlinear decay of an ordinary electromagnetic pump wave into an electro-acoustic wave and an upper-hybrid wave in a two-electron-temperature plasma has been investigated analytically. In contrast with the work of Sharma, Ramamurthy & Yu (1984), it is found that the decay can take place in the absence of the restrictive condition Ti ≫ Te and the plasma be magnetized. Using a hydrodynamical model of the plasma, the nonlinear dispersion relation and growth rate are obtained. A comparison of the present investigation is made with earlier work, and its possible application to the ELMO bumpy torus is discussed.

Parametric decay of an upper-hybrid wave in a plasma cylinder

1997 ◽  
Vol 58 (2) ◽  
pp. 277-285
Author(s):  
S. C. SHARMA
Keyword(s):  
Growth Rate ◽  
Nonlinear Interaction ◽  
Perturbation Technique ◽  
Wave Functions ◽  
Lower Hybrid ◽  
Hybrid Wave ◽  
Lower Hybrid Wave ◽  
Plasma Cylinder ◽  
Coupled Mode ◽  
Parametric Decay

A large-amplitude upper-hybrid wave in a plasma cylinder is susceptible to parametric decay into a lower-hybrid wave and an upper-hybrid wave. The perpendicular and parallel motions of electrons play equally important roles in the nonlinear interaction. The coupled-mode equations are solved using a perturbation technique. The growth rate of the instability is less sensitive to the radial mode number of the sideband. However, for higher-order radial modes it falls off as the overlap of the interacting wave functions decreases.

Scattering of electromagnetic waves by hybrid waves in a two-electron-temperature plasma

1991 ◽  
Vol 46 (1) ◽  
pp. 99-106 ◽  
Author(s):  
S. K. Sharma ◽  
A. Sudarshan
Keyword(s):  
Growth Rate ◽  
Electron Temperature ◽  
High Frequency ◽  
Electromagnetic Waves ◽  
Low Frequency ◽  
Lower Hybrid ◽  
Stimulated Scattering ◽  
Coupled Modes ◽  
Temperature Plasma ◽  
Electrostatic Perturbation

In this paper, we use the hydrodynamic approach to study the stimulated scattering of high-frequency electromagnetic waves by a low-frequency electrostatic perturbation that is either an upper- or lower-hybrid wave in a two-electron-temperature plasma. Considering the four-wave interaction between a strong high-frequency pump and the low-frequency electrostatic perturbation (LHW or UHW), we obtain the dispersion relation for the scattered wave, which is then solved to obtain an explicit expression for the growth rate of the coupled modes. For a typical Q-machine plasma, results show that in both cases the growth rate increases with noh/noc. This is in contrast with the results of Guha & Asthana (1989), who predicted that, for scattering by a UHW perturbation, the growth rate should decrease with increasing noh/noc.

Observation of Parametric Decay of a Pumping Wave in Lower Hybrid Wave Heating and Current Drive Experiments at the FT-2 Tokamak

2019 ◽  
Vol 45 (12) ◽  
pp. 1134-1141 ◽  
Author(s):  
V. V. D’yachenko ◽  
A. N. Konovalov ◽  
A. Yu. Stepanov ◽  
A. B. Altukhov ◽  
E. Z. Gusakov ◽  
...  
Keyword(s):  
Current Drive ◽  
Lower Hybrid ◽  
Hybrid Wave ◽  
Lower Hybrid Wave ◽  
Parametric Decay ◽  
Wave Heating

scholarly journals Excitation of lower hybrid wave by an ion beam in magnetized plasma

2013 ◽  
Vol 31 (4) ◽  
pp. 747-752 ◽  
Author(s):  
Ved Prakash ◽  
Ruby Gupta ◽  
Suresh C. Sharma ◽  
Vijayshri
Keyword(s):  
Growth Rate ◽  
Ion Beam ◽  
Maximum Growth ◽  
Maximum Growth Rate ◽  
Magnetized Plasma ◽  
Unstable Wave ◽  
Lower Hybrid ◽  
Hybrid Wave ◽  
Lower Hybrid Wave ◽  
Beam Density

AbstractLower hybrid wave excitation in magnetized plasma by an ion beam via Cerenkov interaction is studied. The lower hybrid modes showed maximum growth rate of the instability when phase velocity of the lower hybrid mode along the magnetic field is comparable to the electron thermal velocity. We have derived the expression for the maximum growth rate and found that the growth rate of the instability increases with beam density. Moreover, the maximum growth rate of the instability scales as the one-third power of the beam density. The real part of the frequency of the unstable wave increases as almost the square root of the beam energy.

scholarly journals Parametric decay instabilities of lower hybrid wave current drive on CFETR

2020 ◽  
Author(s):  
T. T. Zhou ◽  
N. Xiang ◽  
J. L. Chen ◽  
C. Y. Gan ◽  
G. Z. Jia
Keyword(s):  
Current Drive ◽  
Lower Hybrid ◽  
Hybrid Wave ◽  
Lower Hybrid Wave ◽  
Parametric Decay
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