Speaker
Martina Mrkvickova
(Department of Physical Electronics, Masaryk University, Brno, Czech republic)
Description
The presented study reports on the technique of extraction of the collisional quenching coefficients of the N2(B$^3\Pi_g$) vibrational levels by nitrogen molecule.
The quenching was examined by the laser-induced fluorescence technique in the monofillamentary volume DBD streamer discharge ignited in pure nitrogen at low pressures [1, 2]. The discharge was powered by periodic high-voltage bursts (superimposing two sine-waves, $f_{AC} = 1$ kHz, with a positive pulse of a short duration of 100 ns, all applied at a fixed repetition frequency of 10 Hz). Superposition of the HV pulse during second positive AC half-cycle results in locking the onset of the streamer with respect to the HV pulse and allows fixing arbitrary delay between the streamer and laser pulse.
The quenching of individual vibronic levels was tracked by the LIF scheme described in detail in [2].
Vibrational states of the N$_2$(B$^3\Pi_g$, $\nu = 3-12$) were individually excited by the laser pulse, the fluorescence originated in two different vibronic transitions was then tracked by two different fast photomultipliers and sampled simultaneously by the oscilloscope and multichannel photon-counter. Combination of various approaches enabled recording the long-time development of the fluorescence signal, including the beginning of the pulse, where the photon-counting signal is saturated, and the late fluorescence decay tail, where the signal-to-noise ratio of the oscilloscope is insufficient. The analysis of obtained LIF waveforms reveals the two-term exponential decay, we will discuss the origin of both components. The rate coefficients for electronic quenching of the vibrational levels $\nu = 3-12$ by N$_2$ will be presented. We will also discuss the best practices in the implementation of the LIF technique based on a broadband nanoseconds OPO laser under streamer discharge conditions, as well its advantages and limitations.
**Acknowledgements:**
Work supported by the Czech Science Foundation (GAČR no. GA15-04023S).
**References:**
[1] M Šimek, P F Ambrico and V Prukner, J. Phys. D: Appl. Phys. 46 (2013) 485205, [2] M Šimek, P F Ambrico and V Prukner, J. Phys. D: Appl. Phys. 48 (2015) 265202
Primary author
Martina Mrkvickova
(Department of Physical Electronics, Masaryk University, Brno, Czech republic)
Co-authors
Dr
Milan Simek
(Institute of Plasma Physics of the CAS, Czech Republic)
Dr
Paolo Ambrico
(CNR NANOTEC)
Dr
Vaclav Prukner
(Institute of Plasma Physics v.v.i.)
