During initial studies of ECRH in the HL-1M tokamak, non-standard central MHD activities,such as saturated sawtooth, partially saturated sawtooth, double sawtooth, and the strong m = 1 bursts have been observed while ...During initial studies of ECRH in the HL-1M tokamak, non-standard central MHD activities,such as saturated sawtooth, partially saturated sawtooth, double sawtooth, and the strong m = 1 bursts have been observed while changing the heating location, the ECRH power, the plasma density. Complete suppression of sawtooth is achieved for the duration of the ECRH, when the heating power is applied on the high-field side of low-density plasma, and exceeds a threshold value of power. The m = 1 bursts riding on the ramp phase of sawtooth can only be excited when the ECRH location is near the q = 1 surface on the high field side. The conditions under which the various relaxation activities are produced or suppressed are described. Experimental results imply that the energetic electrons generated during ECRH are responsible for the modification/or stabilization/or excitation of the instability. Near the q = 1 surface, the passing electrons play the role of reducing the shear and tending to stabilize the sawtooth activity, while the barely-trapped electrons play the role of enhancing or driving an internal kink instability.展开更多
Quantum dynamics of a charged particle in a two-dimensional （2D） lattice subject to magnetic and electric fields is a rather complicated interplay between cyclotron oscillations （the case of vanishing electric fiel...Quantum dynamics of a charged particle in a two-dimensional （2D） lattice subject to magnetic and electric fields is a rather complicated interplay between cyclotron oscillations （the case of vanishing electric field） and Bloch oscillations （zero magnetic field）, details of which has not yet been com- pletely understood. In the present work we suggest to study this problem by using cold atoms in optical lattices. We introduce a one-dimensional （1D） model which can be easily realized in labora- tory experiments with quasi-lD optical lattices and show that this model captures many features of the cyclotron-Bloch dynamics of the quantum particle in 2D square lattices.展开更多
文摘During initial studies of ECRH in the HL-1M tokamak, non-standard central MHD activities,such as saturated sawtooth, partially saturated sawtooth, double sawtooth, and the strong m = 1 bursts have been observed while changing the heating location, the ECRH power, the plasma density. Complete suppression of sawtooth is achieved for the duration of the ECRH, when the heating power is applied on the high-field side of low-density plasma, and exceeds a threshold value of power. The m = 1 bursts riding on the ramp phase of sawtooth can only be excited when the ECRH location is near the q = 1 surface on the high field side. The conditions under which the various relaxation activities are produced or suppressed are described. Experimental results imply that the energetic electrons generated during ECRH are responsible for the modification/or stabilization/or excitation of the instability. Near the q = 1 surface, the passing electrons play the role of reducing the shear and tending to stabilize the sawtooth activity, while the barely-trapped electrons play the role of enhancing or driving an internal kink instability.
文摘Quantum dynamics of a charged particle in a two-dimensional （2D） lattice subject to magnetic and electric fields is a rather complicated interplay between cyclotron oscillations （the case of vanishing electric field） and Bloch oscillations （zero magnetic field）, details of which has not yet been com- pletely understood. In the present work we suggest to study this problem by using cold atoms in optical lattices. We introduce a one-dimensional （1D） model which can be easily realized in labora- tory experiments with quasi-lD optical lattices and show that this model captures many features of the cyclotron-Bloch dynamics of the quantum particle in 2D square lattices.
