A thyratron-based pulse generator for fundamental studies of NO{sub x} removal in nonthermal plasmas
In collaboration with the Army Research Laboratory (ARL), the National Institute of Standards and Technology (NIST), and McMaster University, the authors are investigating the removal of NOx from engine exhaust streams using nonthermal plasmas (NTPs). The near-term experiments focus on measuring temperature distributions and reactive species concentrations in electric discharge NTP reactors using laser induced fluorescence (LIF) and tunable diode laser absorption spectroscopy (TDLAS), with first experiments on LIF measurements of OH in a pulsed dielectric-barrier discharge. Because the self extinguishing microdischarges in a conventional (low frequency driven) barrier discharge are both short lived (a few to a few tens of nanoseconds) and randomly distributed in the process volume, it is difficult to measure the time-varying properties of the species produced by the plasma. To synchronize the plasma ignition with the optical diagnostics, a thyratron switched, high voltage pulse generator has been constructed to drive a small dielectric-barrier plasma cell. A fast rise time thyratron tube is used in a low inductance geometry to deliver a negative high voltage pulse to the cell. The output voltage pulse has a rise time of 6.5 ns, a peak voltage of 40 kV, and a repetition rate of 20 Hz. A microdischarge streamer occurs between the pin electrode and the glass barrier during the rise time of the voltage pulse. The delay between the input signal and the microdischarge is 250 ns with a jitter of 4 ns, thus allowing repetitive initiation of a microdischarge with low temporal jitter. The energy per pulse is obtained from the voltage and current versus time, v(t) and i(t), measured at the cell. The fast rising pulse also produces a higher E/N at breakdown in the discharge than in conventional NTP cells, which may affect the removal efficiency of pollutants.
- Research Organization:
- Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
- Sponsoring Organization:
- Department of Defense, Washington, DC (United States)
- DOE Contract Number:
- W-7405-ENG-36
- OSTI ID:
- 650239
- Report Number(s):
- LA-UR-97-3468; CONF-970799-; ON: DE98000252; TRN: AHC2DT04%%152
- Resource Relation:
- Conference: 1997 diesel engine emissions reduction workshop, San Diego, CA (United States), 27-31 Jul 1997; Other Information: PBD: Sep 1997
- Country of Publication:
- United States
- Language:
- English
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