0000000000444788
AUTHOR
J Kuhalainen
The squeezer ion guide
Abstract The properties of an ordinary ion guide can be improved by inserting a grid between the nozzle and the skimmer. When positive ions are transported, an electric potential lower than +10 V is connected to the grid and one of the order of − 10 V to the skimmer. Efficient focusing is achieved between the nozzle and the grid by a combined action of the viscous helium flow field and the weak electric field. The focusing device is called a “squeezer”. It can be extended by adding more grids, a second skimmer, and differential pumping. Contrary to the first grid, the additional elements act more or less like electrostatic lenses in medium vacuum. With the squeezer ion guide, ions created i…
Facility for thermal helium desorption (THDS) measurements
Abstract We describe a thermal helium desorption spectrometer, built at the Department of Physics, University of Jyvaskyla, which will be used in investigations of crystal defects generated by keV range heavy ion bombardment. The helium desorption method and its requirements are reviewed briefly. The structure of the facility itself is presented in detail. The efficiency and the operation of the apparatus is discussed.