Radio frequency hollow cathodes for the plasma processing technology

Particle-in-cell simulations of hollow cathode enhanced capacitively coupled radio frequency discharges

“…Hollow cathodes (HCs) are a type of electrode geometry in both dc and rf plasma systems, which allow for the formation of a hollow cathode effect (HCE). 1 HC systems typically consist of a small hollow cylindrical or rectangular electrode electrically connected through a power generator to a larger grounded electrode. 1,2 Depending on the operating conditions (i.e., gas pressure and applied voltage), a HCE can be initiated, which is characterized by a large increase in current density (and hence plasma density) for a given voltage.…”

“…1 HC systems typically consist of a small hollow cylindrical or rectangular electrode electrically connected through a power generator to a larger grounded electrode. 1,2 Depending on the operating conditions (i.e., gas pressure and applied voltage), a HCE can be initiated, which is characterized by a large increase in current density (and hence plasma density) for a given voltage. This large increase in plasma density has consequently made HCs attractive for a number of applications, including light sources for spectrochemistry, 3 as ionization and neutralization sources in plasma thrusters, 4 ion lasers, 5 and especially as etching and deposition devices in plasma processing.…”

Plasma Oxidation Printing into DLC and Graphite for Surface Functionalization

“…Due to this automatic power matching, the oxygen plasma state was controlled in the response time of 0.1 ms. RF and DC plasmas were ignited independently to work in the experiment. The DC bias was controllable from 0 to −600 V, while RF voltage was controllable from 0 to 250 V. The pressure of oxygen gas was also tunable and controlled to be held constant with the tolerance of 0.1 Pa. As precisely explained in [8], a conductive stainless steel tube with the longitudinal cross section of 20 mm × 40 mm and the thickness of 2 mm was utilized as the hollow cathode to intensify the oxygen ion density up to the order of 10 ions/m 3 . Figure 1.…”

Observations of a mode transition in a hydrogen hollow cathode discharge using phase resolved optical emission spectroscopy

“…Observations of a mode transition in a hydrogen hollow cathode discharge using phase resolved optical emission spectroscopy Sam Dixon, 1,a) Christine Charles, 1 James Dedrick, 1 Two distinct operational modes are observed in a radio frequency (rf) low pressure hydrogen hollow cathode discharge. The mode transition is characterised by a change in total light emission and differing expansion structures.…”

“…Arrayed hollow cathode systems are useful for plasma processing applications due to their high plasma density and scalable geometry. 1 Hydrogen is often used for surface processing applications such as film or crystal growth 2,3 or the deposition of hydrogenated silicon. 4 The "Pocket Rocket" source 5 provides a useful analogue of a single hollow cathode that might appear in such an array.…”