5976

5585

كارشناسي ارشد

فيزيك هسته اي

اصفهان: دانشگاه صنعتي اصفهان، دانشكده فيزيك

1389

يازده،104ص.: مصور،جدول،نمودار

ص.ع.به فارسي و انگليسي

اكبر پروازيان

ظفرالله كلانتري

8/3/90

محمدحسن علامت ساز، احمد شيراني

فيزيك

ID5585

به فارسي و انگليسي: قابل رويت در نسخه ديجيتالي

Parametric Instability Raman Scattering in Plasma Ahmad Naghidokht ahmadnaghidokht@gmail com March 14 2011 Department of Physics Isfahan University of Technology Isfahan 84156 83111 Iran Degree M Sc Language Farsi Dr Akbar Parvazian Mail a parvazin @cc iut ac ir Abstract One of the most important ways for plasma heating is injection of the electromagnetic waves into the plasma After injection of wave into the plasma Parametric Instabilities by considering of match conditions for frequency and wave number can be occur One of these instabilities that much considered is Stimulated Raman Scattering Instability that in this instability an electromagnetic wave decays into another electromagnetic wave and an electron plasma wave Mechanism of this process is justifiable on the basis of the pondermotive force This force by modulation of high frequency waves provides possibility of coupling them with low frequency waves For overdense plasma in Inertial Confinement Fusion laser beams be used for plasma heating that leads to Stimulated Raman Scattering Instability Important parameter in studying this instability is instability rate that for laser beams depends on intensity of laser and density of plasma Electron trapping by wave potential changes instability rate as leads to a frequency shift and oscillation in instability rate Out of the resonance region decay waves can experience landau damping that leads to energy transfer to plasma electrons and finally plasma heating For heating of dense plasma in Magnetic Confinement Fusion radio waves inject into the plasma too For this way Stimulated Raman Scattering Instability occurs too Instability rate in this way depends on pump frequency and density of plasma sensitively so that for pump wave frequency with frequencies 28 58 128 and 138GHz for NSTX instability rate for 28GHz is high by order two compare to 128GHz Resulting high value instability rate for 28GHz that leads to strong damping shows that this frequency is efficient compare to three other frequencies for heating purpose in NSTX With increase in frequency of pump wave and amplifying the electric field the pondermotive force decreases and then instability rate will decrease sensitively too The other parameters such plasma temperature and that is criterion for rate of wave damping into the plasma are effective in instability rate too so that increase of these parameters leads to enhanced instability rate The increase of these parameters will cause the growth of electron plasma wave because the growth of electron plasma wave shows variation of instability rate completely Regarding of increase in Landau damping with increase in and need to initial instability growth achievement to an optimized value for this parameter is necessary Keywords Parametric Instability Stimulated Raman Scattering Instability pondermotive force Instability rate Landau damping NSTX tokamak

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ظفرالله كلانتري

محمدحسن علامت ساز، احمد شيراني