轴向磁场中弱自转对电弧的螺旋不稳定性的影响

Effect of weak rotation to helical instability of arcs in axial magnetic field

为了明确弱自转对电弧的螺旋不稳定性的影响，采用抛物型电导率和与时间有关的线性微扰理论，给出了有弱自转存在的热势分布（温度分布）、稳定性条件以及不稳定性增长率等定量结果；得出了迎着外加磁场方向，自转为顺时针方向时，稳定区域增大；反之。

The helical instability of an arc column with electrical conductivity of the parabolic distribution and weak rotation is discussed in an axial magnetic field. The magnetohydrodynamic equations serve as the starting point of the theory, in an electrostatic approximation and a linear time dependent perturbation theory, the perturbation equations for the arc column movement are deduced. Solutions of these equations are obtained analytically, from which the stability limit of the cylindrical arc and the growth rate of the helical instability are given. Having compared the results with those without rotation, the authors have found that when the rotation is clockwise against the direction of the axial magnetic field, the stable area is enlarged; on the contrary, the stable area is lessened.