Optical and probe measurements of the hollow cathode plasma

Abstract

The distribution of working gas spectral lines and cathode material in the optical radiation of arc discharge plasma with a hollow cathode is investigated. The dependences of the spectral line intensities Xe I-4807.02 Å, Xe II-4844.33 Å and La II-3949.1 Å on the parameters of the external arc column plasma, cathode wall temperature and discharge characteristics are defined. With the help of the probe and spectroscopic measurements the parameters of the cathode internal plasma are determined. The physical processes occurring in the arc with a hollow cathode on the grounds of the experimental data are discussed.

The use of hollow cathodes in deposition processes: A critical review

“…The plasma density of the HCD state depends on the experimental parameters but, as mentioned in the A C C E P T E D M A N U S C R I P T ACCEPTED MANUSCRIPT 53 introduction, typical values are from 10 11 to more than 10 13 cm -3 [18,19], and this is often two orders of magnitude more than the D-HC condition [3,22]. Neutral Ar is the most numerous species and there will be much smaller quantities of Ar* and Having a high density of electrons with sufficient energy to cause the second ionization process is not sufficient; the singly-charged ions must be confined within the plasma region where the second ionization can take place (see page 24 in [159]).…”

“…The term "hollow cathode discharges" has commonly been applied to plasmas in a cathode with a cavity-like geometry, such that the plasma is enclosed or partially bound by the walls that are at the cathode A C C E P T E D M A N U S C R I P T ACCEPTED MANUSCRIPT 5 potential [12][13][14]. Just as the magnetic field trapping of the electrons in a magnetron cathode results in an increase in the plasma density (10 8 -10 11 cm -3 for magnetron sputtering [15]), in the hollow cathode, electron trapping by the geometry of the cathode also results in a higher plasma density, 10 11 to >10 13 cm -3 [16][17][18][19]. However, it is very important to distinguish between the three different types of discharges that can be established in a hollow cathode [20].…”

“…In general, at low powers and/or at relatively low gas pressures, the plasma is a "conventional" discharge characterized by low currents and medium to high voltages (in this work, we will call this a discharge in a hollow cathode or D-HC). Even this simple plasma has a higher density, 10 10 -10 11 cm -3 , than that of a normal planar parallel electrode system because the hollow geometry significantly reduces the loss of electrons [19,21,22]. As we describe in detail later in this study, for an appropriate combination of gas pressure and hollow cathode diameter, as the applied power is increased, the negative glow of the plasma formed in front of the cylindrical surface A C C E P T E D M A N U S C R I P T ACCEPTED MANUSCRIPT 8 the most important aspects of the pressure is that it controls whether the mean free path of the interaction is smaller, or larger, than the dimensions of the discharge.…”

Effect of the Hollow Cathode Heat Power on the Performance of an Hall-Effect Thruster

“…1(a). Its electron emitter is generally made of material with a low work function, such as LaB 6 or Barium Tungsten [2] . Due to the recent fast development in the electric propulsion technology, HCs have also aroused great interest [3∼5] .…”