A high-brightness thermionic microwave electron gun
A high-brightness thermionic microwave electron gun
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DOI：
10.2172/7068490
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发表时间：
1991-02
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影响因子：
--
通讯作者：
M. Borland
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文献类型：
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作者：
M. Borland
在SSRL、AET Associates和Varian Associates的共同努力下，SSRL 150 MeV直线加速器已经设计、制造、测试和安装了一种使用热离子阴极的高亮度微波电子枪。本文讨论了火炮及其相关系统设计和操作背后的物理原理，给出了火炮性能的预测和实验测试。微波枪的概念越来越受到人们的关注，因为它有望提供比传统直流枪技术更高电流、更低发射度的电子束。在直流枪中，加速梯度小于8 mV/m，而在微波枪中，加速梯度可以超过100 mV/m，提供更快的初始加速，从而减少空间电荷的有害影响。微波枪比直流枪产生更高的动量束，因此在随后的束流传输过程中减少了空间电荷效应。典型的直流枪产生的动能为80-400keV，相比之下，SSRL微波枪的动能为2-3 MeV。最先进的微波枪设计采用激光驱动的光电阴极，提供了优异的性能，但具有更高的复杂性和成本。具有磁聚束系统的热离子微波枪在成本和复杂性上与传统系统相当，但提供的性能要好几个数量级。对SSRL微波枪的更多模拟预测，对于由大约50%的从枪发射的粒子组成并且具有动量扩散{正负}10%的束流，存在着归一化的均方根发射度。这些发射率每束最多5{次}10{sup 9}e{sup{负}}。在枪和直线加速器之间的传输线上的色差增加到通常-lt；30{pi}{center_dot}m{sube}{center_dot}{u}m。
In a collaborative effort by SSRL, AET Associates, and Varian Associates, a high-brightness microwave electron gun using a thermionic cathode has been designed, built, tested, and installed for use with the SSRL 150 MeV linear accelerator. This thesis discusses the physics behind the design and operation of the gun and associated systems, presenting predictions and experimental tests of the gun`s performance. The microwave gun concept is of increasing interest due to its promise of providing higher-current, lower-emittance electron beams than possible from conventional, DC gun technology. In a DC guns, accelerating gradients are less than 8 MV/m, while those in a microwave gun can exceed 100 MV/m, providing much more rapid initial acceleration, thereby reducing the deleterious effects of space-charge. Microwave guns produce higher momentum beams than DC guns, thus lessening space-charge effects during subsequent beam transport. Typical DC guns produce kinetic energies of 80--400 KeV, compared to 2--3 MeV for the SSRL microwave gun. ``State-of-the-art`` microwave gun designs employ laser-driven photocathodes, providing excellent performance but with greater complexity and monetary costs. A thermionic microwave gun with a magnetic bunching system is comparable in cost and complexity to a conventional system, but provides performance that is orders of magnitude better.more » Simulations of the SSRL microwave gun predict a normalized RMS emittance at the gun exist of < 10 {pi} {center_dot} m{sub e}c {center_dot} {mu}m for a beam consisting of approximately 50% of the particles emitted from the gun, and having a momentum spread {plus_minus}10%. These emittances are for up to 5 {times} 10{sup 9}e{sup {minus}} per bunch. Chromatic aberrations in the transport line between the gun and linear accelerator increase this to typically < 30 {pi} {center_dot} m{sub e} {center_dot} {mu}m.« less