GLAss Spherical Tokamak(GLAST-Ⅲ)is a spherical tokamak with an insulating vacuum vessel that has a unique single-passage capability for incident microwaves.In this work,electron cyclotron resonance heating(ECRH)-assi...GLAss Spherical Tokamak(GLAST-Ⅲ)is a spherical tokamak with an insulating vacuum vessel that has a unique single-passage capability for incident microwaves.In this work,electron cyclotron resonance heating(ECRH)-assisted plasma pre-ionization in GLAST-Ⅲis explored for three radio-frequency(RF)polarizations(the O-,X-,and M-modes)at different toroidal-field(TF)strengths and filled gas pressures.The optimum hydrogen pressure is identified for efficient plasma pre-ionization.A comparison of the plasma pre-ionizations initiated by the O-,X-,and M-modes shows prominent differences in the breakdown time,location,and wave absorption.In the case of O-mode polarization,microwave absorption occurs for a relatively shorter duration,resulting in a bell-shaped electron-temperature(Te)temporal profile.Microwave absorption is dominant in the case of the X-mode,leading to a broader Te temporal profile.The M-mode discharge contains features of both the X-and O-modes.Efficient plasma pre-ionization is achieved in the X-mode polarization for the intermediate TF strengths(with a central toroidal magnetic field B0=0.075 T).Traces of the electron-number density show a similar tendency,as revealed by Te.These results suggest that the X-mode is the best candidate for efficient plasma pre-ionization at low filled gas pressures(10-2 Pa)in small tokamaks.展开更多
We study matter accretion onto Einstein-aether black holes by adopting the Hamiltonian approach.The general solution of accretion is discussed using the isothermal equation of state.Different types of fluids are consi...We study matter accretion onto Einstein-aether black holes by adopting the Hamiltonian approach.The general solution of accretion is discussed using the isothermal equation of state.Different types of fluids are considered,including ultra-relativistic,ultra-stiff,sub-relativistic,and radiation fluids,and the accretion process onto Einstein-aether black holes is analyzed.The behavior of the fluid flow and the existence of critical points is investigated for Einstein-aether black holes.We further discuss the general expression and behavior of polytropic fluid onto Einstein-aether black holes.The most important feature of this work is the investigation of the mass accretion rate of the above-mentioned fluids and the comparison of our findings with the Schwarzschild black hole,which generates particular signatures.Moreover,the maximum mass accretion rate occurs near the Killing and universal horizons,and the minimum accretion rate lies between them.展开更多
基金partially supported by a Grant-in-Aid from the Planning Commission,Government of Pakistan and IAEA Co-ordinated research project(CRP-F13018)under research grant PAK-22840。
文摘GLAss Spherical Tokamak(GLAST-Ⅲ)is a spherical tokamak with an insulating vacuum vessel that has a unique single-passage capability for incident microwaves.In this work,electron cyclotron resonance heating(ECRH)-assisted plasma pre-ionization in GLAST-Ⅲis explored for three radio-frequency(RF)polarizations(the O-,X-,and M-modes)at different toroidal-field(TF)strengths and filled gas pressures.The optimum hydrogen pressure is identified for efficient plasma pre-ionization.A comparison of the plasma pre-ionizations initiated by the O-,X-,and M-modes shows prominent differences in the breakdown time,location,and wave absorption.In the case of O-mode polarization,microwave absorption occurs for a relatively shorter duration,resulting in a bell-shaped electron-temperature(Te)temporal profile.Microwave absorption is dominant in the case of the X-mode,leading to a broader Te temporal profile.The M-mode discharge contains features of both the X-and O-modes.Efficient plasma pre-ionization is achieved in the X-mode polarization for the intermediate TF strengths(with a central toroidal magnetic field B0=0.075 T).Traces of the electron-number density show a similar tendency,as revealed by Te.These results suggest that the X-mode is the best candidate for efficient plasma pre-ionization at low filled gas pressures(10-2 Pa)in small tokamaks.
基金Pakistan for its financial support under the grant No:9290/Balochistan/NRPU/R&D/HEC/2017。
文摘We study matter accretion onto Einstein-aether black holes by adopting the Hamiltonian approach.The general solution of accretion is discussed using the isothermal equation of state.Different types of fluids are considered,including ultra-relativistic,ultra-stiff,sub-relativistic,and radiation fluids,and the accretion process onto Einstein-aether black holes is analyzed.The behavior of the fluid flow and the existence of critical points is investigated for Einstein-aether black holes.We further discuss the general expression and behavior of polytropic fluid onto Einstein-aether black holes.The most important feature of this work is the investigation of the mass accretion rate of the above-mentioned fluids and the comparison of our findings with the Schwarzschild black hole,which generates particular signatures.Moreover,the maximum mass accretion rate occurs near the Killing and universal horizons,and the minimum accretion rate lies between them.
