Pejman KHORSHID - Academia.edu (original) (raw)

Papers by Pejman KHORSHID

Research paper thumbnail of Magnetohydrodynamic Activity During Limiter Biasing on the CT-6B Tokamak

Chinese Physics Letters, 2001

Research paper thumbnail of Large amplitude dust ion acoustic solitons: considering dust polarity and nonextensive electrons

The characteristics of arbitrary amplitude dust ion acoustic solitary waves (DIASWs) are studied ... more The characteristics of arbitrary amplitude dust ion acoustic solitary waves (DIASWs) are studied in unmagnetized dusty plasmas whose constituents are cold uid ions, nonextensive electrons and stationary negative/positive dust particles. The pseudopotential approach has been used to investigate the structure of localized waves. It is found that, solitary waves exist in a definite interval for the Mach number which depends sensitively to the electron nonextensivity and dust polarity. Our results can be useful to understand the properties of localized electrostatic disturbances that may occur in astrophysical and space dusty plasmas.

Research paper thumbnail of Singular Value Decomposition Combined With Analytical Method for Tokamak Plasma Tomography

Journal of Fusion Energy, 2009

Research paper thumbnail of Optical thickness corrections to ECE measurement of electron temperature in IR-T1 tokamak

Journal of Plasma Physics, 2012

The Electron Cyclotron Emission (ECE) radiation has been investigated, passing through plasma col... more The Electron Cyclotron Emission (ECE) radiation has been investigated, passing through plasma column with concerning absorption effect on the IR-T1 tokamak. The intensity of second harmonic X-mode is used to investigate changes in electron temperature profile. The results show that radiation temperature (Trad) detected outside the plasma column is less than the electron temperature (Te) in the core. The radiation temperature can be directly interpreted as Te to about 3–10% reduction. This implies that optical thickness and electron density effects are more considerable at lower temperatures.

Research paper thumbnail of Magnetohydrodynamic Activity During Limiter Biasing on the CT-6B Tokamak

Chinese Physics Letters, 2001

... KHORSHID Pejman12, WANG Long(¦£)1, YANG Xuan-Zong(©¨)1, FENG Chun-Hua(¡ ¢)1, ZHANG Peng-Yun(«... more ... KHORSHID Pejman12, WANG Long(¦£)1, YANG Xuan-Zong(©¨)1, FENG Chun-Hua(¡ ¢)1, ZHANG Peng-Yun(«¤ª)1, QI Xia-Zhi(¥§¬)1, ROUHANI Shahriar2, RAHIMITABAR M. Reza3, AGHAMIR M. Farzin2, GHORANNEVISS Mahmud2, HANTEZADEH M. Reza2 ½Institute of ...

Research paper thumbnail of Edge Plasma Behavior During Externally Applied Positive Biasing and Resonant Magnetic Perturbation in IR-T1 Tokamak

ABSTRACT Edge plasma behavior during externally applied positive biasing and resonant helical mag... more ABSTRACT Edge plasma behavior during externally applied positive biasing and resonant helical magnetic field (RHF) perturbation in IR-T1 tokamak has been investigated. The experiments have been done in different regimes as electrode and limiter biasing, magnetic perturbation application and both of them. The profiles of radial electron temperature, floating potential, poloidal and toroidal rotation velocity have been measured by using of a movable Langmuir probe and Mach probes in the edge of plasma. Magnetohydrodynamic phenomena based on Mirnov oscillations have been investigated by applying the positive biasing potentials and RHF's. An effect of RHF on magnetohydrodynamics behaviour during positive biasing has been investigated. The results shown that subsequent to the application of a positive bias, an increase in the frequency of poloidal magnetic field fluctuations was observed but after RHF application during L = 2 and n = 1 (L=poloidal and n=toroidal turn) the m = 2 MHD mode oscillations amplified and m = 3 mode is suppressed; also by applying L = 3 the m = 2 mode oscillation has been disappeared. The results analyzed by SVD and wavelet methods. The toroidal velocity changes after a short delay time of about td = 0.5 - 1.5 ms during RHF application while poloidal velocity changes just after RHF's. The poloidal velocity increased after positive bias during RHF (L = 2 mode) application but it decreased after positive biasing during RHF (L = 3 mode) regime. Toroidal velocity hasn't considerable change during biasing but its behaviour smoothed after positive bias application.

Research paper thumbnail of 1 EX / P 4-15 Overview of Experimental Studies on IRT 1 Tokamak

An overview of experimental studies on IR-T1 tokamak is presented. Several issues of plasma displ... more An overview of experimental studies on IR-T1 tokamak is presented. Several issues of plasma displacement measurement are investigated. An analytic solution of the Biot–Savart law, which is used to calculate magnetic fields created by toroidal plasma current, is presented. Results of calculations are compared with the experimental data obtained in no-plasma shots with a toroidal current-carrying coil positioned inside the vessel to simulate the plasma movements. The results show a good linear behavior of plasma position measurements. An array of Mirnov coils employed for measurement of plasma position, too. The results show that Mirnov array can not be used for this measurement without concerning high field side errors. An external resonant helical magnetic field (RHF) applied to plasma. The aim of these experiments was to understand the effect of RHF on light impurities radiation and horizontal displacement measurements. Measurements results of visible line emissions of O, C impurit...

Research paper thumbnail of MHD Instabilities and Toroidal Field Effects on Plasma Column Behavior in Tokamak

AIP Conference Proceedings, 2006

... Iran, Islamic Republic of)] ; Wang, L. [Institute of Physics, Chinese Academy of Sciences, 10... more ... Iran, Islamic Republic of)] ; Wang, L. [Institute of Physics, Chinese Academy of Sciences, 100080-603, Beijing (China)] ; Ghoranneviss, M. ; Arvin, R. ; Dorranian, D. ; Talebitaher, A. ; Salem, MK ; Abhari, A. [Plasma Physics Research Center, Islamic Azad University, 14665-678 ...

Research paper thumbnail of Different Methods for Measuring Plasma Displacement in Tokamaks, Construction & Compensation of Continuous Coils in IR-T1 Tokamak

AIP Conference Proceedings, 2008

The measurement of current-carrying plasma column displacement is very important for plasma posit... more The measurement of current-carrying plasma column displacement is very important for plasma position control. Two methods for this purpose are introduced. In this paper, calculation and construction of these coils is explained. Multiple moment method has been used and derived for construction of sensing coils Also Fourier Transform has been used and derived for continuous coils. The comparison of their

Research paper thumbnail of Study of Plasma Interaction with Titanium Coated Ferritic Steel in IR-T1 Tokamak

AIP Conference Proceedings, 2008

Research paper thumbnail of Designing a Sine-Coil for Measurement of Plasma Displacements in IR-T1 Tokamak

AIP Conference Proceedings, 2008

A method for the measurement of the plasma position in the IR-T1 tokamak in toroidal coordinates ... more A method for the measurement of the plasma position in the IR-T1 tokamak in toroidal coordinates is developed. A sine-coil, which is a Rogowski coil with a variable wiring density is designed and fabricated for this purpose. An analytic solution of the Biot-Savart law, which is used to calculate magnetic fields created by toroidal plasma current, is presented. Results of calculations are compared with the experimental data obtained in no-plasma shots with a toroidal current-carrying coil positioned inside the vessel to simulate the plasma movements. The results are shown a good linear behavior of plasma position measurements. The error is less than 2.5% and it is compared with other methods of measurements of the plasma position. This method will be used in the feedback position control system and tests of feedback controller parameters are ongoing.

Research paper thumbnail of Dependence of edge fluctuations on the disruption in tokamak plasmas

The 31st IEEE International Conference on Plasma Science, 2004. ICOPS 2004. IEEE Conference Record - Abstracts.

Summary form only given. Turbulence in magnetically confined plasmas continues to be one of the m... more Summary form only given. Turbulence in magnetically confined plasmas continues to be one of the most important scientifically challenging research topics in controlled thermonuclear fusion research. Turbulence manifests itself as fluctuations in plasma parameters such as the density, temperature, magnetic field and electrostatic potential. The formation of the edge MHD modes may be caused by the fluctuations. In this work

Research paper thumbnail of The effect of limiter biasing on the plasma edge rotation and MHD activities

International Journal of Modern Physics: Conference Series, 2014

Plasma edge rotations and magnetohydrodynamic behaviors have been studied during radial electric ... more Plasma edge rotations and magnetohydrodynamic behaviors have been studied during radial electric field variations in IR-T1 tokamak. An external positive limiter bias has been used as an external radial electric field. The profiles of radial electric field, floating potential, poloidal and toroidal rotation velocities and MHD activities have been studied during positive limiter bias. The poloidal and toroidal velocities reduced when the bias was applied and their fluctuations on the plasma edge became smoother furthermore. A significant excitation in dominant mode (4, 1) oscillation amplitude and a sharp decrease in magnetic island rotation frequency have been seen.

Research paper thumbnail of Plasma confinement improvement by RHF in IR-T1 tokamak

IEEE Conference Record - Abstracts. 1996 IEEE International Conference on Plasma Science

Summary form only given. It has been known that tokamak plasma parameters and energy confinement ... more Summary form only given. It has been known that tokamak plasma parameters and energy confinement time may be reduced by plasma impurity radiation. The plasma MHD stabilities may also be influenced by the impurities. Experiments have been performed on the IR-T1 tokamak to investigate the influence of magnetic perturbations and impurities radiation on confinement. IR-T1 is a small air core

Research paper thumbnail of Radial Electric Field and its Influence on Poloidal Magnetic Field Oscillations in the IR-T1 Tokamak

Journal of Fusion Energy, 2009

... Oscillations in the IR-T1 Tokamak Hamid Bolourian • Pejman Khorshid • Mahmoud Ghoranneviss •S... more ... Oscillations in the IR-T1 Tokamak Hamid Bolourian • Pejman Khorshid • Mahmoud Ghoranneviss •Siamak Mohammadi • Reza Arvin • Mahgam Gheydi ... Fusion 47, 479 (2007) 8. R. Shariatzadeh, M. Ghoranneviss, M. Emami, A. Anvari, G. Van Oost, J. Fusion Energ. ...

Research paper thumbnail of Overview of Resonant Helical Magnetic Field Experiments on the IR-T1 Tokamak

Research paper thumbnail of Electron Temperature Measurement in IR-T1 Tokamak by ECE Diagnostic

Journal of Fusion Energy, 2009

ABSTRACT A suitable instrument for electron temperature measurement in Tokamak is electron cyclot... more ABSTRACT A suitable instrument for electron temperature measurement in Tokamak is electron cyclotron emission diagnostic. We used a heterodyne radiometer in Iran-Tokamak-1 (IR-T1) to measure this parameter. This 5 channel system works in K α-band and has a very fast response time and good resolution frequency for IR-T1 tokamak. This receiver was used outside the Tokamak, perpendicular to B t, and with second harmonic of X-mode, variation of electron temperature was measured.

Research paper thumbnail of Study of preparing diamond films in presence of magnetic field by the DC plasma

IEEE Conference Record - Abstracts. 1996 IEEE International Conference on Plasma Science

... for the login options. Ghoranneviss, M.; Masnavi, M.; Khademian, A.; Khorshid, P.; Mehr, MZ; ... more ... for the login options. Ghoranneviss, M.; Masnavi, M.; Khademian, A.; Khorshid, P.; Mehr, MZ; Mirzaei, J.; Plasma Phys. Res. Centre, Tehran. This paper appears in: Plasma Science, 1996. IEEE Conference Record - Abstracts ...

Research paper thumbnail of Mode Analysis with Autocorrelation Method (Single Time Series) in Tokamak

Journal of Fusion Energy, 2010

... S. Saadat (&) Á MK Salem Á M. Goranneviss Plasma Physics Research Center, Islamic... more ... S. Saadat (&) Á MK Salem Á M. Goranneviss Plasma Physics Research Center, Islamic Azad University, Tehran Science & Research Campus, Punak Ave, POBox 14665-678, Tehran, Iran e-mail: shnst577@yahoo.com MK Salem e-mail: mkssalem@gmail.com ...

Research paper thumbnail of MHD Instabilities and Their Effects on Plasma Column Behavior in Tokamak

In the edge plasma of the CT-6B tokamak the poloidal rotation velocity based on MHD behavior has ... more In the edge plasma of the CT-6B tokamak the poloidal rotation velocity based on MHD behavior has been studied. We found that mode number and rotation frequency of plasma column are different in angle position, so that the phase data detected from Mirnov coils array located in poloidal angle on the inner side of chamber is more than outer side which it can be because of toroidal magnetic field effects. It shows that plasma column behaves as non-Rigid body plasma. A relative correction coefficient has been suggested for optical diagnostic purposes. It is observed that when mode number achieves to m=2/n=1, plasma treats like rigid body and almost it leads to a major disruption. The results have been compared with measurements via Mach probe and Doppler shift of H-alpha line spectroscopy. In addition, during positive limiter bias application the poloidal magnetic field oscillations first decreased and then after a delay time it increased with a faster speed. With contribution of viscous force effects in the radial force balance equation for limiter biasing, in terms of the non-stationary model, it allows us to identify the understanding physics responsible for change in the Mirnov oscillations that could be related to poloidal rotation velocity and radial electric field.

Research paper thumbnail of Magnetohydrodynamic Activity During Limiter Biasing on the CT-6B Tokamak

Chinese Physics Letters, 2001

Research paper thumbnail of Large amplitude dust ion acoustic solitons: considering dust polarity and nonextensive electrons

The characteristics of arbitrary amplitude dust ion acoustic solitary waves (DIASWs) are studied ... more The characteristics of arbitrary amplitude dust ion acoustic solitary waves (DIASWs) are studied in unmagnetized dusty plasmas whose constituents are cold uid ions, nonextensive electrons and stationary negative/positive dust particles. The pseudopotential approach has been used to investigate the structure of localized waves. It is found that, solitary waves exist in a definite interval for the Mach number which depends sensitively to the electron nonextensivity and dust polarity. Our results can be useful to understand the properties of localized electrostatic disturbances that may occur in astrophysical and space dusty plasmas.

Research paper thumbnail of Singular Value Decomposition Combined With Analytical Method for Tokamak Plasma Tomography

Journal of Fusion Energy, 2009

Research paper thumbnail of Optical thickness corrections to ECE measurement of electron temperature in IR-T1 tokamak

Journal of Plasma Physics, 2012

The Electron Cyclotron Emission (ECE) radiation has been investigated, passing through plasma col... more The Electron Cyclotron Emission (ECE) radiation has been investigated, passing through plasma column with concerning absorption effect on the IR-T1 tokamak. The intensity of second harmonic X-mode is used to investigate changes in electron temperature profile. The results show that radiation temperature (Trad) detected outside the plasma column is less than the electron temperature (Te) in the core. The radiation temperature can be directly interpreted as Te to about 3–10% reduction. This implies that optical thickness and electron density effects are more considerable at lower temperatures.

Research paper thumbnail of Magnetohydrodynamic Activity During Limiter Biasing on the CT-6B Tokamak

Chinese Physics Letters, 2001

... KHORSHID Pejman12, WANG Long(¦£)1, YANG Xuan-Zong(©¨)1, FENG Chun-Hua(¡ ¢)1, ZHANG Peng-Yun(«... more ... KHORSHID Pejman12, WANG Long(¦£)1, YANG Xuan-Zong(©¨)1, FENG Chun-Hua(¡ ¢)1, ZHANG Peng-Yun(«¤ª)1, QI Xia-Zhi(¥§¬)1, ROUHANI Shahriar2, RAHIMITABAR M. Reza3, AGHAMIR M. Farzin2, GHORANNEVISS Mahmud2, HANTEZADEH M. Reza2 ½Institute of ...

Research paper thumbnail of Edge Plasma Behavior During Externally Applied Positive Biasing and Resonant Magnetic Perturbation in IR-T1 Tokamak

ABSTRACT Edge plasma behavior during externally applied positive biasing and resonant helical mag... more ABSTRACT Edge plasma behavior during externally applied positive biasing and resonant helical magnetic field (RHF) perturbation in IR-T1 tokamak has been investigated. The experiments have been done in different regimes as electrode and limiter biasing, magnetic perturbation application and both of them. The profiles of radial electron temperature, floating potential, poloidal and toroidal rotation velocity have been measured by using of a movable Langmuir probe and Mach probes in the edge of plasma. Magnetohydrodynamic phenomena based on Mirnov oscillations have been investigated by applying the positive biasing potentials and RHF's. An effect of RHF on magnetohydrodynamics behaviour during positive biasing has been investigated. The results shown that subsequent to the application of a positive bias, an increase in the frequency of poloidal magnetic field fluctuations was observed but after RHF application during L = 2 and n = 1 (L=poloidal and n=toroidal turn) the m = 2 MHD mode oscillations amplified and m = 3 mode is suppressed; also by applying L = 3 the m = 2 mode oscillation has been disappeared. The results analyzed by SVD and wavelet methods. The toroidal velocity changes after a short delay time of about td = 0.5 - 1.5 ms during RHF application while poloidal velocity changes just after RHF's. The poloidal velocity increased after positive bias during RHF (L = 2 mode) application but it decreased after positive biasing during RHF (L = 3 mode) regime. Toroidal velocity hasn't considerable change during biasing but its behaviour smoothed after positive bias application.

Research paper thumbnail of 1 EX / P 4-15 Overview of Experimental Studies on IRT 1 Tokamak

An overview of experimental studies on IR-T1 tokamak is presented. Several issues of plasma displ... more An overview of experimental studies on IR-T1 tokamak is presented. Several issues of plasma displacement measurement are investigated. An analytic solution of the Biot–Savart law, which is used to calculate magnetic fields created by toroidal plasma current, is presented. Results of calculations are compared with the experimental data obtained in no-plasma shots with a toroidal current-carrying coil positioned inside the vessel to simulate the plasma movements. The results show a good linear behavior of plasma position measurements. An array of Mirnov coils employed for measurement of plasma position, too. The results show that Mirnov array can not be used for this measurement without concerning high field side errors. An external resonant helical magnetic field (RHF) applied to plasma. The aim of these experiments was to understand the effect of RHF on light impurities radiation and horizontal displacement measurements. Measurements results of visible line emissions of O, C impurit...

Research paper thumbnail of MHD Instabilities and Toroidal Field Effects on Plasma Column Behavior in Tokamak

AIP Conference Proceedings, 2006

... Iran, Islamic Republic of)] ; Wang, L. [Institute of Physics, Chinese Academy of Sciences, 10... more ... Iran, Islamic Republic of)] ; Wang, L. [Institute of Physics, Chinese Academy of Sciences, 100080-603, Beijing (China)] ; Ghoranneviss, M. ; Arvin, R. ; Dorranian, D. ; Talebitaher, A. ; Salem, MK ; Abhari, A. [Plasma Physics Research Center, Islamic Azad University, 14665-678 ...

Research paper thumbnail of Different Methods for Measuring Plasma Displacement in Tokamaks, Construction & Compensation of Continuous Coils in IR-T1 Tokamak

AIP Conference Proceedings, 2008

The measurement of current-carrying plasma column displacement is very important for plasma posit... more The measurement of current-carrying plasma column displacement is very important for plasma position control. Two methods for this purpose are introduced. In this paper, calculation and construction of these coils is explained. Multiple moment method has been used and derived for construction of sensing coils Also Fourier Transform has been used and derived for continuous coils. The comparison of their

Research paper thumbnail of Study of Plasma Interaction with Titanium Coated Ferritic Steel in IR-T1 Tokamak

AIP Conference Proceedings, 2008

Research paper thumbnail of Designing a Sine-Coil for Measurement of Plasma Displacements in IR-T1 Tokamak

AIP Conference Proceedings, 2008

A method for the measurement of the plasma position in the IR-T1 tokamak in toroidal coordinates ... more A method for the measurement of the plasma position in the IR-T1 tokamak in toroidal coordinates is developed. A sine-coil, which is a Rogowski coil with a variable wiring density is designed and fabricated for this purpose. An analytic solution of the Biot-Savart law, which is used to calculate magnetic fields created by toroidal plasma current, is presented. Results of calculations are compared with the experimental data obtained in no-plasma shots with a toroidal current-carrying coil positioned inside the vessel to simulate the plasma movements. The results are shown a good linear behavior of plasma position measurements. The error is less than 2.5% and it is compared with other methods of measurements of the plasma position. This method will be used in the feedback position control system and tests of feedback controller parameters are ongoing.

Research paper thumbnail of Dependence of edge fluctuations on the disruption in tokamak plasmas

The 31st IEEE International Conference on Plasma Science, 2004. ICOPS 2004. IEEE Conference Record - Abstracts.

Summary form only given. Turbulence in magnetically confined plasmas continues to be one of the m... more Summary form only given. Turbulence in magnetically confined plasmas continues to be one of the most important scientifically challenging research topics in controlled thermonuclear fusion research. Turbulence manifests itself as fluctuations in plasma parameters such as the density, temperature, magnetic field and electrostatic potential. The formation of the edge MHD modes may be caused by the fluctuations. In this work

Research paper thumbnail of The effect of limiter biasing on the plasma edge rotation and MHD activities

International Journal of Modern Physics: Conference Series, 2014

Plasma edge rotations and magnetohydrodynamic behaviors have been studied during radial electric ... more Plasma edge rotations and magnetohydrodynamic behaviors have been studied during radial electric field variations in IR-T1 tokamak. An external positive limiter bias has been used as an external radial electric field. The profiles of radial electric field, floating potential, poloidal and toroidal rotation velocities and MHD activities have been studied during positive limiter bias. The poloidal and toroidal velocities reduced when the bias was applied and their fluctuations on the plasma edge became smoother furthermore. A significant excitation in dominant mode (4, 1) oscillation amplitude and a sharp decrease in magnetic island rotation frequency have been seen.

Research paper thumbnail of Plasma confinement improvement by RHF in IR-T1 tokamak

IEEE Conference Record - Abstracts. 1996 IEEE International Conference on Plasma Science

Summary form only given. It has been known that tokamak plasma parameters and energy confinement ... more Summary form only given. It has been known that tokamak plasma parameters and energy confinement time may be reduced by plasma impurity radiation. The plasma MHD stabilities may also be influenced by the impurities. Experiments have been performed on the IR-T1 tokamak to investigate the influence of magnetic perturbations and impurities radiation on confinement. IR-T1 is a small air core

Research paper thumbnail of Radial Electric Field and its Influence on Poloidal Magnetic Field Oscillations in the IR-T1 Tokamak

Journal of Fusion Energy, 2009

... Oscillations in the IR-T1 Tokamak Hamid Bolourian • Pejman Khorshid • Mahmoud Ghoranneviss •S... more ... Oscillations in the IR-T1 Tokamak Hamid Bolourian • Pejman Khorshid • Mahmoud Ghoranneviss •Siamak Mohammadi • Reza Arvin • Mahgam Gheydi ... Fusion 47, 479 (2007) 8. R. Shariatzadeh, M. Ghoranneviss, M. Emami, A. Anvari, G. Van Oost, J. Fusion Energ. ...

Research paper thumbnail of Overview of Resonant Helical Magnetic Field Experiments on the IR-T1 Tokamak

Research paper thumbnail of Electron Temperature Measurement in IR-T1 Tokamak by ECE Diagnostic

Journal of Fusion Energy, 2009

ABSTRACT A suitable instrument for electron temperature measurement in Tokamak is electron cyclot... more ABSTRACT A suitable instrument for electron temperature measurement in Tokamak is electron cyclotron emission diagnostic. We used a heterodyne radiometer in Iran-Tokamak-1 (IR-T1) to measure this parameter. This 5 channel system works in K α-band and has a very fast response time and good resolution frequency for IR-T1 tokamak. This receiver was used outside the Tokamak, perpendicular to B t, and with second harmonic of X-mode, variation of electron temperature was measured.

Research paper thumbnail of Study of preparing diamond films in presence of magnetic field by the DC plasma

IEEE Conference Record - Abstracts. 1996 IEEE International Conference on Plasma Science

... for the login options. Ghoranneviss, M.; Masnavi, M.; Khademian, A.; Khorshid, P.; Mehr, MZ; ... more ... for the login options. Ghoranneviss, M.; Masnavi, M.; Khademian, A.; Khorshid, P.; Mehr, MZ; Mirzaei, J.; Plasma Phys. Res. Centre, Tehran. This paper appears in: Plasma Science, 1996. IEEE Conference Record - Abstracts ...

Research paper thumbnail of Mode Analysis with Autocorrelation Method (Single Time Series) in Tokamak

Journal of Fusion Energy, 2010

... S. Saadat (&) Á MK Salem Á M. Goranneviss Plasma Physics Research Center, Islamic... more ... S. Saadat (&) Á MK Salem Á M. Goranneviss Plasma Physics Research Center, Islamic Azad University, Tehran Science & Research Campus, Punak Ave, POBox 14665-678, Tehran, Iran e-mail: shnst577@yahoo.com MK Salem e-mail: mkssalem@gmail.com ...

Research paper thumbnail of MHD Instabilities and Their Effects on Plasma Column Behavior in Tokamak

In the edge plasma of the CT-6B tokamak the poloidal rotation velocity based on MHD behavior has ... more In the edge plasma of the CT-6B tokamak the poloidal rotation velocity based on MHD behavior has been studied. We found that mode number and rotation frequency of plasma column are different in angle position, so that the phase data detected from Mirnov coils array located in poloidal angle on the inner side of chamber is more than outer side which it can be because of toroidal magnetic field effects. It shows that plasma column behaves as non-Rigid body plasma. A relative correction coefficient has been suggested for optical diagnostic purposes. It is observed that when mode number achieves to m=2/n=1, plasma treats like rigid body and almost it leads to a major disruption. The results have been compared with measurements via Mach probe and Doppler shift of H-alpha line spectroscopy. In addition, during positive limiter bias application the poloidal magnetic field oscillations first decreased and then after a delay time it increased with a faster speed. With contribution of viscous force effects in the radial force balance equation for limiter biasing, in terms of the non-stationary model, it allows us to identify the understanding physics responsible for change in the Mirnov oscillations that could be related to poloidal rotation velocity and radial electric field.