High-Efficiency Plasma Source Using a Magnetic Mirror Trap for Miniature-Ion Pumps

Abstract

In this study, we design a highly efficient plasma source using a magnetic mirror trap with two opposing permanent magnets for a miniature high-efficiency ion pump. First, we simulated the distribution of the magnetic field line formed by the proposed magnetic mirror configuration. By optimizing the distance between two opposing permanent magnets and size of these magnets, a magnetic mirror ratio value of 27 could be obtained, which is an electron confinement efficiency of over 90%. We also conducted an experiment on a high-efficiency discharge plasma source for a miniature ion pump using an optimized magnetic circuit. As a result, we revealed that the proposed magnetic circuit has a pronounced effect on plasma generation, particularly in the high-vacuum region.

Ultra-High Vacuum Cells Realized by Miniature Ion Pump Using High-Efficiency Plasma Source

“…To measure the discharge current of the ion pump as a function of vacuum pressure, the unsealed ion pump was installed within the small vacuum chamber made of borosilicate glass with a volume of about 360 cm 3 . To achieve a high-efficiency miniature plasma source utilizing a magnetic mirror trap, magnets embedded within a yoke were mounted outside the electrode section of the ion pump, according to our previous work [ 14 ]. After setting up the unsealed ion pump, the small vacuum chamber was evacuated using a turbo molecular pump and dry scroll vacuum pump down to an ultra-high vacuum.…”

“…This reduction makes it difficult to generate the discharge and diminishes the vacuum pumping capability. To address this issue, we have previously proposed a highly efficient miniature plasma source utilizing a magnetic mirror trap, which employs two opposing permanent magnets [ 14 ].…”

“…This study presents the successful realization of ultra-high vacuum cells through the utilization of a miniature ion pump integrated with a high-efficiency plasma source, which used the new-type magnetic circuit we have reported in [ 14 ]. The geometry of the ion pump is employed not only in pumps but also in Penning vacuum gauges.…”