Microhollow cathode discharges

Abstract

The current–voltage characteristics of hollow cathode discharges and their predischarges in argon under dc and pulsed conditions were found to have a positive slope at pressures up to approximately 50 Torr, and currents up to 20 mA, at a hole diameter of 0.7 mm. In this range of pressure and current, parallel operation of hollow cathode discharges, without ballast, was demonstrated. Scaling to higher pressure is possible by reducing the hole diameter. Pulsed experiments with an array of cathode rings of 75 μm diameter allowed us to obtain parallel operation of more than 50 discharges at a pressure of 350 Torr in air.

Hollow cathode sustained plasma microjets: Characterization and application to diamond deposition

“…1 Figure 4 compares the appearance of an Ar plasma microjet formed in 178 and 508 m diameter tubes as seen through a concentric metal aperture 1 mm in diameter which serves as the anode. In the smaller diameter tube ͓Fig.…”

“…1 It has been found experimentally that reducing the cathode hole diameter to near 100 m allows operation at atmospheric pressure in rare gases such as neon, 2 argon, 3 and xenon. 3 In one version, a planar electrode geometry is used consisting of a layered structure ͑ϳ200 m thick͒ of two metal plates on either side of a dielectric spacer with a hole through the structure.…”

“…11 Operation at high pressures in the hollow cathode mode requires shrinking of the hole diameter to sizes similar to those found in planar microdischarges such that the pressure times hole diameter (p•d) is on the order of 10 Torr cm. 1 Formation of microdischarges in a flow geometry would take advantage of the properties of a hollow cathode and could be attractive for thin film deposition. 12 Moreover, the overall size encourages use in microelectromechanical systems applications where a miniaturized plasma source is desirable.…”

Optimizing drive parameters of a nanosecond, repetitively pulsed microdischarge high power 121.6 nm source

“…Whereas previous versions of this system utilized MgF 2 focusing lenses [15], this system makes use of a series of focusing mirrors which eliminate chromatic aberration associated with a lens setup. The power is calculated applying the known solid angle of the spectrograph and efficiency of the spectrograph and treating the MD as a point source with spherically isotropic emission, as is common in MD-VUV studies [16]. The power measured by the VUV spectrograph was found to be within 10% of the value measured using a VUV calibrated photodiode.…”

Reduced adhesion of human blood platelets to polyethylene tubing by microplasma surface modification

“…1 In this work, we describe a approach for treating smalldiameter polymer tubing and we make use of two microplasma diagnostics to monitor the plasma properties during the treatment process. The microplasma, which extends along the entire length of the tubing, is created with hollow cathode (HC) electrodes [37][38][39] which are placed in vacuum at each end of the PE tubing. This discharge configuration has many advantages compared to previous techniques.…”