Optical Emission Studies of the NRL Plasma Torch for the Shipboard Waste Treatment Program
Abstract
Optical emission spectroscopy is employed to characterize the plasma in the NRL torch operating at approx. 100 kW DC power. Both non-transferred and transferred arc configurations are considered. The working gas of the torch is nitrogen with a 5% admixture of hydrogen. Atomic emission lines are measured and analyzed using a local thermodynamic equilibrium (LTE) and a collisional radiative equilibrium (CRE) model. The core of the arc is found to be close to LTE, with a central plasma temperature of 6,200 deg K in the non-transferred mode, and approx. 15,000 deg K in the transferred mode. However, the periphery of the arc is far from thermal and excitation equilibrium. Radiative photo-pumping by the hot core, included in the CRE model, is found to play a significant role in controlling excited level populations. Stark broadened H sub Beta measurements of the non-transferred arc indicate an anomalously high electron density. For the transferred arc the plasma radiation accounts for approx. 50% of the energy input to the plasma. Finally, the electrical properties of long transferred arcs are found to change during slag processing due to entrainment of volatized slag material with low ionization potential. This suggests an on-line diagnostic for the process state of the treated waste.
Document Details
- Document Type
- Technical Report
- Publication Date
- Feb 26, 1999
- Accession Number
- ADA360841
Entities
People
- D. A. Counts
- J. L. Giuliani
- J. Rogerson
- P. Kepple
- R. W. Clark
Organizations
- United States Naval Research Laboratory