Investigation on Energy Discrimination in a Direct Energy Converter for Deuterium-Helium-3 Fusion

我们在尖点型直接能量转换器（Cupp-type Direct Energy Converter，简称DCPDEC）中进行了电荷分离和能量鉴别的原理验证实验。DCPDEC是一种将D^3He燃料聚变堆产生的热离子直接转换为电能的高效能量转换器。在该装置中，电子从入射等离子体流中分离，热离子在第二个尖点偏转到能量转换器中，聚变质子不受两个尖点的影响，我们建立了一个基本的实验装置，用于测试电子与离子的电荷分离和热离子与聚变离子的能量分辨。低能等离子体束被注入到一个单尖点，线尖点和点尖点出口处的电荷收集器监测电荷流。当磁场被调节以形成尖点时，到尖点的电流变为正，到线尖点的电流变为负，这表明电子和离子分离。分离比随尖点处磁曲率的增大而增大。数值模拟得到了电子和离子在二维会切磁场中的运动轨迹。研究发现，在入射半径和俯仰角一定的条件下，可以实现电荷分离。实验装置上安装了一个可变能量的离子源，验证了尖形场的能量鉴别作用。对于更高的离子能量，点尖点的离子电流变得大于线尖点的离子电流，示出了能量鉴别的原理证明。

We perform a proof-of-principle experiment of a charge separation and energy discrimination in a cusp-type direct energy converter (CUSPDEC), which was proposed as an efficient energy converter from thermal ions poduced by D-^3He fueled fusion reactor directly into electricity. In the CUSPDEC, electrons are separated from the incident plasma stream at the first cusp and the thermal ions are deflected at the second cusp to an energy converter with fusion protons not being affected by the two cusps.We have constructed a basic experimental device for testing the charge separation of electrons from ions and the energy discrimination of thermal and fusion ions. The low enrgy plasma beam is injected to a single cusp and the charge collectors at the line cusp and the point cusp exit monitor the charge flow. When the magnetic field is adjusted to form the cusp, the current to the point cusp becomes positive and that to the line cusp becomes negative showing the separation of electrons and ions. The separation ratio increases with the increased magnetic curvature at the cusp point. A numerical simulation is performed, in which the trajectory of electrons and ions are obtained in the two-dimensional cusp magnetic field. It is found that the charge separation can be obtained under the condition that the incident radius and pitch angle are within a certain value. This result is consistent with the experimental result.The experimental device is equipped with an ion source with variable energy to prove the energy discrimination by the cusp field. The ion current to the point cusp becomes larger than to the line cusp for higher ion energy, showing the proof-of-principle of the energy discrimination.