胡椒孔法在强流脉冲离子束中的发射度测量

摘要

真空弧离子源的引出束流具有低能、强流等特点,当离子源工作在单脉冲模式时,被广泛采用的缝-杯式和Alison式发射度测量方法不再适用.采用基于成像板的胡椒孔法测量了真空弧离子源的发射度.初步研制了胡椒孔法发射度测量装置,利用该装置测量了引出电压为64 kV时脉冲束流的发射度和发射相图.在x方向和y方向,测得归一化均方根发射度分别为6.41,4.61 c·mm· mrad.测量结果表明该真空弧离子源在64 kV时的归一化发射度远大于其他类型的离子源的发射度.%A pepper pot-imaging plate system has been developed and used to measure the 4-D transverse emittance of a vacuum arc ion source.Single beam pulses of tens to hundreds milliamperes were extracted from the plasma with 64 kV high voltage.An imaging plate was laid after the pepper pot to visualize the ion beamlets passing though the holes on the pepper pot.An application program was developed to show the phase-space distribution and calculate the ellipse and RMS emittances.The normalized RMS emittances are about 6.41 π · mm · mrad in r-direction and 4.61 π · mm · mrad in y-direction.It is shown that the emittance of the vacuum arc ion source is much larger than that of other types of ion sources,which is mainly attributed to the high current and the convex meniscus of this source.