Toroidal plasmoid generation via extreme hydrodynamic shear

Brandenburg

2022

One of the primary basic plasma parameters within transient nonequilibrium plasmas is the reduced electric field strength, roughly understood as the ratio of the electrical energy given to the charged species between two collisions. While physical probes have historically been used for electric field measurements, recent advances in high intensity lasers and sensitive detection methods have allowed for non-invasive optical electric field determination in nearly any discharge configuration with time-resolution up to the sub-nanosecond range and sub-millimeter spatial resolution. This topical review serves to highlight several non-invasive methods for in-situ electric field strength determination in transient plasmas ranging from high vacuum environments to atmospheric pressure and above. We will discuss the advantages and proper implementation of (i) Laser induced fluorescence dip spectroscopy for measurements in low pressure RF discharges, (ii) optical emission spectroscopy based methods for nitrogen, helium or hydrogen containing discharges, (iii) electric field induced coherent Raman scattering, and (iv) electric field induced second harmonic generation. The physical mechanism for each method will be described as well as basic implementation and highlighting recent results.

Section: Oes Methods Based On Collision Radiative Schemesmentioning

confidence: 99%

“…The limitations of the method connected to temporal and spatial resolution for streamer diagnostics are obvious. Issues connected to the spatiotemporally averaged optical emission signal detection were subject of several investigations [29,31,32,[38][39][40][41][42]59].…”

Section: Oes Methods Based On Collision Radiative Schemesmentioning

confidence: 99%

Electric field determination in transient plasmas: in situ & non-invasive methods

Goldberg

Brandenburg

2022

“…in [2]. For the reasons above, the intensity ratio of spectral bands of the FNS and the second positive system (SPS) of N 2 can be used as an indirect non-invasive spectroscopic method of obtaining the reduced electric field in nitrogen containing discharges [3][4][5][6][7][8][9]. The ratio itself is typically calculated from the intensity of the FNS (0, 0) band and SPS (0, 0) band.…”

Section: S  S + +mentioning

confidence: 99%

Electric field determination in air plasmas from intensity ratio of nitrogen spectral bands: I. Sensitivity analysis and uncertainty quantification of dominant processes

Obrusník

Bı́lek

et al. 2018

The ratio of the spectral band intensities of the first negative and second positive spectral systems of molecular nitrogen is a well recognized method for indirect determination of the electric field. It is applied for various plasmas, e.g. barrier and corona discharges for industrial applications or geophysical plasmas occurring in the Earth’s atmosphere. The method relies on the dependence of the intensity ratio R(E/N) of selected bands on the reduced electric field strength. Both experimental and theoretical approaches have been used to determine this dependence, yet there still is a rather large spread in the data available in literature. The primary aim of this work is to quantify the overall uncertainty of the theoretical R(E/N) dependence and identify the main sources of this uncertainty. As the first step we perform sensitivity analysis on a full N2/O2 plasma kinetics model to find a minimal set of processes that are influential for the R(E/N) dependence. It is found to be in agreement with simplified kinetic models generally used. Subsequently, we utilize Monte Carlo-based uncertainty quantification to provide a confidence band for the electric field obtained from the theoretical R(E/N) dependence. Finally, subsequent steps are proposed to significantly reduce the uncertainty of the method.

“…) is widely recognized spectroscopic signature for quantification of the reduced electric field strength in air-like discharges [1][2][3][4][5][6][7][8][9].…”

Section: Introductionmentioning

confidence: 99%

Electric field determination in air plasmas from intensity ratio of nitrogen spectral bands: II. Reduction of the uncertainty and state-of-the-art model

Bı́lek

Obrusník

et al. 2018

An established and widely used method for remote electric field determination is based on the ratio of the spectral band intensities of the first negative and second positive spectral systems of molecular nitrogen which does, however, require theoretically or experimentally obtained dependence R ( E / N ) . The aim of this work is to reduce the overall uncertainty in the theoretical dependence R ( E / N ) calculated in part I of this work. We present an in-depth review of the kinetic and cross section data that are available in literature for the most influential processes. By tracking the historical evolution of the kinetic data, their cross-validation by independent authors and by taking into account advances in the experimental methods, we separate datasets that have not been rendered inaccurate by later works. By doing so, we reduce the uncertainty of the theoretical R ( E / N ) dependence and propose corresponding confidence band to be used by scientific community.