Power dissipation, gas temperatures and electron densities of cold atmospheric pressure helium and argon RF plasma jets

Abstract

A set of diagnostic methods to obtain the plasma parameters including power dissipation, gas temperature and electron density is evaluated for an atmospheric pressure helium or argon radio frequency (RF) plasma needle for biomedical applications operated in open air. The power density of the plasma is more or less constant and equal to 1.3 × 10 9 W m −3 . Different methods are investigated and evaluated to obtain the gas temperature. In this paper the gas temperatures obtained by rotational spectra of OH(A-X) and N + 2 (B-X) are compared with Rayleigh scattering measurements and measurements of the line broadening of hydrogen and helium emission lines. The obtained gas temperature ranges from 300 to 650 K, depending on the gas. The electron densities are estimated from the Stark broadening of the hydrogen α and β lines which yield values between 10 19 and 10 20 m −3 . In the case of helium, this is an overestimate as is shown by a power balance from the measured power density in the plasma jet. The obtained plasma parameters enable us to explain the radial contraction of the argon plasma compared with the more diffuse helium plasma. The accuracy of all considered diagnostics is discussed in detail.

Hydrogen Peroxide Production in an Atmospheric Pressure RF Glow Discharge: Comparison of Models and Experiments

“…To calculate the power dissipated by the plasma alone, it is necessary to correct the applied power (P applied = P f orward − P re f lected ) going into the matching box and the reactor for the losses in the matching box. The temperature of the coil was measured for both on and off cases, showing no significant difference in temperature between plasma on and off at a given current, allowing us to assume the same losses occur in the matching box at a given current as shown previously in a similar system [27].…”

Power measurement for an atmospheric pressure plasma jet at different frequencies: distribution in the core plasma and the effluent

“…Therefore the input power without plasma P 0 is measured for the same current value every time to estimate power losses, e.g. heat loss at the inductance [17]. The difference between input power with and without plasma results in the plasma power P plasma in the device "head".…”

“…Hence the difference of the two power values should result in the power dissipated into the "effluent". The following set of equations is used [17,18]:…”

Jet‐to‐jet interactions in atmospheric‐pressure plasma jet arrays for surface processing

“…It is because in He discharge, the relative importance of diffusion compared to the dissociative recombination is much higher in the case of Ar. [31] Therefore, it is much easier to obtain diffusive discharge in He than in Ar.…”

“…Some studies also proved that Ar is more energy efficient to produce active species and therefore has a higher efficacy in sterilization. [6,31] The investigation and comparison of He and Ar plasma jet array discharge characteristics and discharge mechanisms, especially the jet-to-jet interaction mechanism at different discharge parameters, are important for the achievement of proper performance in different applications. In this paper, the comparative studies of He and Ar 1D plasma jet arrays with cross-field needle-ring electrode structure are performed using electrical measurements, optical images of the discharges, Schlieren photograph, and ICCD images.…”