THREE DIMENSIONAL STUDY ON PULSAR MAGNETOSPHERE WHICH CREATES ELECTRON-POSITRON PAIRS

脉冲星磁层中粒子加速机理的研究大多是在轴对称的情况下进行的，因为在非轴对称的情况下，即磁轴与旋转轴倾斜的情况下，分析是非常困难的。这个项目挑战了这种不结盟的情况。请注意，真正的脉冲星系统确实是非对准的完全三维系统。虽然我们必须处理大量的数值计算，但我们通过使用专用计算机克服了这个问题。使用一种特殊的计算机使这个项目有别于其他作品。(1)第一步，我们解析地研究了场向电场的形成，该电场加速了极帽上的粒子。磁力线有两种：向旋转轴弯曲的磁力线和远离旋转轴弯曲的磁力线。有人提出，加速度只发生在“向磁场线”上。然而，我表明，如果电流密度大于临界值，粒子加速发生，而不考虑场线曲率。这种加速度足以引起电子-正电子对产生级联。(2)在非对准情况下，存在位移电流对场结构的影响。对流对磁场结构也有影响。考虑这两种效应，我们计算了无力情况下垂直旋转器的场结构。（Mestel和Shibata， 1998年准备）(3)我在特殊的鼠用计算机Harp-3 （2.2Gflops）上开发了三维磁层模型的粒子代码。Hape-3最初是为引力相互作用的粒子设计的，但我们用它来研究库仑相互作用。这个代码将被用来研究一个电球，在这个电球中产生对。这是今后磁层对放电粒子模拟计算的重要一步。

Mechanism of particle acceleration in the pulsar magnetosphere is mostly studied in the axisymmetric case because analysis in non-axisymmetric case, i.e., in the case that the magnetic axis is inclined to the rotation axis, is tremendously difficult. This project callenges to this non-aligned case. Note the real pulsar system is indeed non-aligned completely three dimensional system. Although we have to deal with large numerical calculation, we overcome this problem by using a special porpouse computer. The use of a special porpouse computer makes this project distinctive to other works.(1) In the first step, we analytically study the formation of the field-aligned electric field, which accelerate particles on the polar caps. There are two kind of magnetic field lines : the field lines curving toward the rotation axis and those curving away the rotation axis. It was proposed that acceleration takes place only on the 'toward field lines'. However, I showed that particle acceleration takes place regardless of field line curvature if the current density is larger than a critical value. This acceleration is shown to be strong enough to cause electron-positron pair creation cascade. (Shibata 1997)(2) In the non-aligned case, there is an effect of the displacement current on the field structure. The convection current also contribute to the field structure. Including the both effects, we calculate the field structure of the perpendicular rotator in the force-free case. (Mestel and Shibata, 1998 in preparation)(3) I developed a particle-code for the three-dimensional magnetospheric model on the special porpouse computer Harp-3 (2.2Gflops). Hape-3 was original made for gravitationary interacting particles, but we use it for Coulomb interaction. This code will be used to study a electrosphere in which pair creation takes place. This is an important step for the future calculation for particle simulation of the magnetosphere with pair discharge.