Kulkarni D D, Ahl C D, Shore A M, Miller A J, Harriss J E, Sosolik C E, Marler J P
Department of Physics and Astronomy, Clemson University, Clemson, South Carolina 29634, USA.
Rev Sci Instrum. 2017 Aug;88(8):083306. doi: 10.1063/1.4997962.
Using a retarding field analyzer, we have measured offsets between the nominal and measured kinetic energy of multicharged ions extracted from an electron beam ion source (EBIS). By varying source parameters, a shift in ion kinetic energy was attributed to the trapping potential produced by the space charge of the electron beam within the EBIS. The space charge of the electron beam depends on its charge density, which in turn depends on the amount of negative charge (electron beam current) and its velocity (electron beam energy). The electron beam current and electron beam energy were both varied to obtain electron beams of varying space charge and these were related to the observed kinetic energy offsets for Ar and Ar ion beams. Knowledge of these offsets is important for studies that seek to utilize slow, i.e., low kinetic energy, multicharged ions to exploit their high potential energies for processes such as surface modification. In addition, we show that these offsets can be utilized to estimate the effective radius of the electron beam inside the trap.
我们使用了一个减速场分析仪，测量了从电子束离子源（EBIS）引出的多电荷离子的标称动能与测量动能之间的偏移量。通过改变源参数，离子动能的偏移归因于EBIS内电子束空间电荷产生的俘获势。电子束的空间电荷取决于其电荷密度，而电荷密度又取决于负电荷的量（电子束电流）及其速度（电子束能量）。我们改变电子束电流和电子束能量以获得具有不同空间电荷的电子束，并将这些与观察到的Ar和Ar离子束的动能偏移相关联。对于试图利用慢速（即低动能）多电荷离子来利用其高势能进行诸如表面改性等过程的研究而言，了解这些偏移很重要。此外，我们表明这些偏移可用于估计阱内电子束的有效半径。
