Development of High-Rep-Rate Ion Induced Secondary Emission Electron Gun and Its Application

设计、制造和测试了一种适用于气体处理的二次发射电子枪，该电子枪安装在离子源旁边，称为线状离子等离子体源(WIPS)。在电子枪中，从WIPS中提取的离子被加速朝向阴极表面，阴极表面设置为倾斜于离子轨迹。通过离子的碰撞，从阴极表面发射的二次电子被加速朝向电子窗口，并形成非常宽的电子束。位于电子枪和气体处理室之间的电子窗口与离子引出窗口垂直设置，并且是地球上的电位。为了设计一种能垂直于电子窗口注入电子束的阴极结构，对几种情况下的离子和电子轨迹进行了数值模拟。随后，根据加速电压高达100KV时的离子和电子束电流来评估电子枪的特性。在电子窗口处放置由蜂窝板支撑的15μm厚的铝箔，作为电子枪和气体处理室之间的真空密封。在真空条件下，对气体处理室内的电子束电流分布进行了评估。在气体处理室内检测到均匀的电子束。用于气体处理的电子束横截面较大(64.5 cm^2)，电流密度约为15 mA/cm^2。预计这样的电流密度水平将提供一种有效的NOX处理方法。

A secondary emission electron gun applicable to a gas treatment was designed, fabricated and tested.The gun is set beside an ion source, which is called a wire ion plasma source (WIPS). In the gun, ions extracted from the WIPS are accelerated toward a cathode surface, which is set oblique to the ion loci. By collision of ions, secondary electrons emitted from the cathode surface are then accelerated toward the electron window and form a very wide electron beam. The electron window, which is between the electron gun and a gas treatment chamber, is set orthogonal to the ion extraction window and is on earth potential. In order to design a structure of cathode, which can inject the electron beam perpendicular to the electron window, the ion and the electron trajectories were numerically simulated for several conditions. The characteristic of the electron gun has been subsequently evaluated in terms of ion and electron beam currents at the accelerating voltage up to 100 kV.A 15 μm thick aluminum foil supported by a honeycomb board is placed at the electron window as a vacuum seal between the electron gun and the gas treatment chamber. The electron beam current distribution inside the gas treatment chamber has been evaluated in a vacuum condition. A uniform electron beam has been detected inside the gas treatment chamber. A relatively large cross section (64.5 cm^2) electron beam with a current density of about 15 mA/cm^2 is available for the gas treatment. It is expected that such current density level will offer an efficient NO_X treatment.