The Accelerating Motion of Solar Coronal Loops (Ⅰ) (Ⅱ)

The ejection of coronal mass in the form of loop transients was discovered during the skylab, and the white-light coronagraph shows that the outward motion of the coronal transients accelerated or remained at an approximately constont velocity. These loops were like elongated structures. The magnatic energy density for the transient was about 10 times the thermal energy density, indicating that the plasma was magnetically controlled.There are four types of the theoretical models of coronal transients-the purely hydrodynamical mode, the MHD numerical modeling mode, the ring current mode and the eruptive prominence and transient mode. As to the first two types one problem is that they evoke purely thermal or nonmagnetic driving forces. Since the magnetic energy dominates in these events (β<1), a nonmagnetic driving mechanism is difficult to justify.In the first paper, the Anzer's model is restudied. the equilibrium in the direction of the minor radius of the loop is analysed, and the driving force produced by the plasma pressure is considered. The equation of motion of a section of the coronal loop top and the minimum current of the accelerated motion of the coronal loop are given, and the numerical calculation is completed for the given different initial conditions.In the second paper, we suggest a magnetic loop model, in which the coronal loop is a loop-like magnetic tube of force. The forces driving the coronal loop are produced by the nonhomogeneous distribution of the longitudinal magnetic fields in the magnetic loop. The coronal loop is a slender one.Given the distribution of the longitudinal magnetic fields on the coronal loop B_Z=B₀r₁ⁿ, n=1, 2, 3, ……where B₀ is a constant, after analysing the various forces that are exerted on the top fo the coronal loop, one can obtain the equation of motion of the coronal loop top (d²R)/(dt²)=(n f(R)ra²B_a²)/(4(n+1)f(R₀)Rr₀)-g(1/R)²The numerical calculations from Equation (1) is completed for the given different initiol conditions. The results are compared with those observed during the skylab period from May 1973 to January 1974. The former is largely in accordance with the later.