A progressively reduced pretension method to fabricate Bradbury-Nielsen gates with uniform tension

摘要

A Bradbury-Nielsen gate (BNG) is often used to modulate ion beams. Itconsists of two interleaved and electrically isolated sets of wires withuniform tension, which can keep parallel, equidistant, and coplanar over a widetemperature range, making the BNG reliable and robust. We have previouslyanalyzed the non-uniform problem of wire tensions with sequentially windingmethod, and developed a template-based transfer method to solve this problem.In this paper, we introduced a progressively reduced pretension method, whichallows directly and sequentially winding wires on the substrate without using atemplate. Theoretical analysis shows that by applying proper pretension to eachwire when fixing it onto the substrate, the final wire tensions of all wirescan be uniform. The algorithm and flowchart to calculate the pretensionsequence are given, and the fabrication process is introduced in detail.Pretensions are generated by weights combination with a homebuilt weavingdevice. A BNG with stainless steel wire and a printed circuit board substrateis constructed with this method. The non-uniformity of the final wire tensionsis less than 2.5% in theory. The BNG is successfully employed in our homemadeion mobility spectrometer, and the measured resolution is 33.5 at a gateopening time of 350 {\mu}s. Compared to the template-based method, this methodis simpler, faster and more flexible when making BNGs with differentconfigurations.