Electron density measurements of atmospheric-pressure non-thermal N2 plasma jet by Stark broadening and irradiance intensity methods

Abstract

Estimation of electron temperature and density of the decay plasma in a laser-assisted discharge plasma extreme ultraviolet source by using a modified Stark broadening method An atmospheric-pressure non-thermal plasma jet excited by high frequency alternating current using nitrogen is developed and the electron density in the active region of this plasma jet is investigated by two different methods using optical emission spectroscopy, Stark broadening, and irradiance intensity method. The irradiance intensity method shows that the average electron density is about 10 20 /m 3 which is slightly smaller than that by the Stark broadening method. However, the trend of the change in the electron density with input power obtained by these two methods is consistent. V C 2014 AIP Publishing LLC. [http://dx.

Electron characterization in weakly ionized collisional plasmas: from principles to techniques

“…For further insights, the electrons in plasma jets has also been characterized using various electron diagnostic techniques, such as laser Thomson scattering [76][77][78], laser interferometry [79], Stark broadening of hydrogen atomic lines [80][81][82], and continuum radiation [84]. The line broadening method has been widely used for most electron studies in atmospheric-pressure plasmas, particularly in microwave-and radio-frequency-excited plasmas because of their high n e .…”

“…Hofmann et al [80] estimated the electron density in 11.7 MHz argon and helium plasma jets based on the Stark broadening of H α and H β lines, which yielded n e values between 10 13 and 10 14 cm −3 . Rarely, some groups [81,82] have reported n e values on the order of 10 14 cm −3 for plasma jets driven at tens of kHz. Laser interferometry, which is one of the promising n e diagnostic tools for pulsed plasmas, provided time-averaged n e on the order of 10 14 cm −3 in a 500 Hz-pulsed helium plasma jet [79].…”

Coupling ofN2+rotational states in an air laser from tunnel-ionized nitrogen molecules

“…As the wavelength difference of the P -branch photons from J and 26-J states is less than 0.006 nm for all the J numbers, it is impossible to directly separate these photons from their spectra because of the limited resolution of our spectrometer (ß0.06 nm). In fact, there exist several spectrum-broadening mechanisms in plasma, such as the thermal Doppler broadening, collisional broadening, Stark broadening, and so on [25,26]. Estimation of the broadened linewidth based on these effects is extremely difficult due to the lack of precise knowledge of many important parameters, such as the plasma density, plasma temperature, strength of the laser field, etc.…”

An inductive RF discharge in water vapor for atomic-emission spectrometry

“…Recently, there has been an increased interest in the properties of water vapor as a plasma-forming gas for the listed applications since water vapor is a relatively cheap raw material which dissociates in the discharge to form highly reactive oxygen and OH hydroxyl. The presence of atomic hydrogen in the plasma allows a relatively easy spectrometric analysis of parameters such as the plasma temperature and electron concentration from the hydrogen Balmer series [2].…”