Sartori E, Agostinetti P, Dal Bello S, Marcuzzi D, Serianni G, Sonato P, Veltri P
Consorzio RFX, Euratom-ENEA association, C.so Stati Uniti 4, 35127 Padova, Italy.
Rev Sci Instrum. 2014 Feb;85(2):02B308. doi: 10.1063/1.4827677.
In negative ion electrostatic accelerators a considerable fraction of extracted ions is lost by collision processes causing efficiency loss and heat deposition over the components. Stripping is proportional to the local density of gas, which is steadily injected in the plasma source; its pumping from the extraction and acceleration stages is a key functionality for the prototype of the ITER Neutral Beam Injector, and it can be simulated with the 3D code AVOCADO. Different geometric solutions were tested aiming at the reduction of the gas density. The parameter space considered is limited by constraints given by optics, aiming, voltage holding, beam uniformity, and mechanical feasibility. The guidelines of the optimization process are presented together with the proposed solutions and the results of numerical simulations.
在负离子静电加速器中，相当一部分引出离子会因碰撞过程而损失，这会导致效率损失以及部件上的热沉积。剥离与稳定注入等离子体源中的气体局部密度成正比；从引出和加速阶段抽气是ITER中性束注入器原型的一项关键功能，并且可以用三维代码AVOCADO进行模拟。为了降低气体密度，测试了不同的几何解决方案。所考虑的参数空间受到光学、瞄准、电压保持、束均匀性和机械可行性等方面限制的约束。给出了优化过程的指导方针以及所提出的解决方案和数值模拟结果。
