  A plasma window (PW) is a device for separating two areas of different
pressures while letting particle beams pass with little to no loss. It has been
introduced by A. Hershcovitch. In the course of this publication, the
properties of a PW with apertures of 3.3 mm and 5.0 mm are presented.
Especially the link between the pressure properties relevant for applications
in accelerator systems and the underlying plasma properties depending on
external parameters are presented. At the low pressure side around some mbar,
high-pressure values reached up to 750 mbar while operating with volume flows
between 1 slm and 4 slm (standard liter per minute) and discharge currents
ranging from 45 A to 60 A. Unique features of the presented PW include
simultaneous plasma parameter determination and the absence of ceramic
insulators between the cooling plates. Optical analysis reveals no significant
damage or wear to the components after an operation time well over 10 h,
whereas the cathode needle needs replacement after 5 h.
