Studies of High Energy Single Particle Confinement in Helical Systems.

为了利用现有的实验装置研究α粒子的运动，我们利用新近发展的“仿星器四极法”在Heliotron DR中测量了高能（E<1 keV）电子在相对较低的磁场强度（B-500 G）下的禁闭。在1996年的实验中，我们使用了一个有网状阳极的电子枪，因此，电子被发射到各个方向。在这个实验中，我们观察到，电子约束恶化时，只有在外侧的环面灯丝和阳极之间的偏置电压增加。这一结果是由电子布居的增加与更高的螺距角解释。在1997年，我们使用了一个电子枪，它有一个小的电子束提取孔。因此，电子以限定的俯仰角发射。在这个实验中，我们观察到，电子约束恶化，在高俯仰角的外围区域的外侧的环面，虽然对俯仰角的依赖是相当温和的数值计算相比。这一结果与以前的实验一致，在实验中，电子被发射到各个方向。磁轴偏移对电子约束的影响也已被检查和约束改善已被观察到与磁轴向内偏移。上述实验结果与数值计算定性一致。

To investigate motion of alpha particles using existing experimental devices, we have measured confinement of energetic (E<1keV) electrons at relatively low magnetic field intensity (B-500G) in Heliotron DR using the newly developed "stellarator tetrode method". In the experiment in 1996, we used an electron gun which had a mesh anode, thus, electrons were launched in all the directions. In this experiment, we observed that electron confinement was deteriorated only at the outboard side of the torus when the bias voltage between the filament and the anode was increased. This result was explained by increase of electron population with higher pitch angles. In 1997, we used an electron gun which had a small beam extracting hole. Thus, electrons were launched at defined pitch angles. In this experiment, we observed that the electron confinement was deteriorated at high pitch angles at the periphery region of the outboard side of the torus although the dependence on the pitch angle was rather mild compared with numerical calculation. This result is consistent with that of previous experiment in which electrons were launched in all directions. Effect of the magnetic axis shift on the electron confinement has also been examined and confinement improvement has been observed with inward shift of the magnetic axis. Above experimental results agree qualitatively with the numerical calculation.