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

脉冲星磁层中的粒子加速机制主要是在轴对称的情况下研究的，因为在非轴对称的情况下，即磁轴向旋转轴倾斜的情况下，分析是非常困难的。这个项目呼应了这个不结盟的案例。请注意，真正的脉冲星系统确实是完全三维的非对齐系统。虽然我们必须处理大量的数值计算，但我们使用了一台专用的便携式计算机来克服这个问题。专用便携式计算机的使用使该项目有别于其他工作。(1)在第一步中，我们解析地研究了场向电场的形成，它加速了极帽上粒子的形成。有两种磁力线：向旋转轴弯曲的磁力线和远离旋转轴的磁力线。有人提出，加速只发生在“朝向磁力线”上。然而，我证明了，如果电流密度大于临界值，无论场线曲率如何，粒子加速都会发生。这种加速被证明足够强，足以引起电子-正电子对的产生级联。(Shibata 1997)(2)在非对齐的情况下，场结构上存在位移电流的影响。对流对场结构也有贡献。在考虑这两种影响的情况下，我们计算了无力情况下垂直旋转体的场结构。(Mestel和Shibata，1998正在准备中)(3)我在专用便携式计算机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制造的，但我们将其用于库仑相互作用。这个代码将被用来研究在其中发生配对产生的电球体。这是对放电磁层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.