Panitzsch Lauri, Peleikis Thies, Stalder Michael, Wimmer-Schweingruber Robert F
Institute for Experimental and Applied Physics (IEAP), Christian-Albrechts-Universität, Kiel, Germany.
Rev Sci Instrum. 2011 Sep;82(9):093302. doi: 10.1063/1.3637462.
In this paper we present our measurements of charge-state and current-density distributions performed in very close vicinity (15 mm) of the extraction of our hexapole geometry electron cyclotron resonance ion source. We achieved a relatively high spatial resolution reducing the aperture of our 3D-movable extraction (puller) electrode to a diameter of only 0.5 mm. Thus, we are able to limit the source of the extracted ion beam to a very small region of the plasma electrode's hole (Ø = 4 mm) and therefore to a very small region of the neutral plasma sheath. The information about the charge-state distribution and the current density in the plane of the plasma electrode at each particular position is conserved in the ion beam. We determined the total current density distribution at a fixed coaxial distance of only 15 mm to the plasma electrode by remotely moving the small-aperture puller electrode which contained a dedicated Faraday cup (FC) across the aperture of the plasma electrode. In a second measurement we removed the FC and recorded m/q-spectra for the different positions using a sector magnet. From our results we can deduce that different ion charge-states can be grouped into bloated triangles of different sizes and same orientation at the extraction with the current density peaking at centre. This confirms observations from other groups based on simulations and emittance measurements. We present our measurements in detail and discuss possible systematic errors.
在本文中，我们展示了在我们的六极几何电子回旋共振离子源提取口非常近的位置（15毫米）进行的电荷态和电流密度分布测量。我们通过将三维可移动提取（引出）电极的孔径减小到仅0.5毫米的直径，实现了相对较高的空间分辨率。因此，我们能够将提取的离子束源限制在等离子体电极孔（直径 = 4毫米）的一个非常小的区域，从而限制在中性等离子体鞘层的一个非常小的区域。在离子束中保留了每个特定位置处等离子体电极平面内电荷态分布和电流密度的信息。我们通过在等离子体电极孔径上远程移动包含专用法拉第杯（FC）的小孔径引出电极，在距等离子体电极仅15毫米的固定同轴距离处确定了总电流密度分布。在第二次测量中，我们移除了法拉第杯，并使用扇形磁铁记录不同位置的m/q谱。从我们的结果可以推断，在提取时，不同的离子电荷态可以分组为不同大小且方向相同的膨胀三角形，电流密度在中心处达到峰值。这证实了其他小组基于模拟和发射度测量的观察结果。我们详细介绍了我们的测量，并讨论了可能的系统误差。
