Enthalpy Measurement in Inductively Heated Plasma Generator Flow by Laser Absorption Spectroscopy

Abstract

Laser absorption spectroscopy was applied for diagnostics of inductively heated plasma generator flows. Temporal variation of translational temperature was deduced from measured absorption line broadening because the flow properties fluctuated at 300 Hz in synchronization with the induction current. The specific total enthalpy and mole fraction of oxygen were estimated from the deduced temperature assuming thermochemical equilibrium. Consequently, the averaged degree of dissociation of oxygen is 0.92. The specific total enthalpy was estimated at 33.7 ± ± 2.9 MJ/kg; 39% of it was in the form of chemical potential. The results show good agreement with intrusive measurements.

Laser Induced Fluorescence Combined with Laser Absorption Spectroscopy for Optically Thick Plasma Diagnostics

“…Laser absorption spectroscopy (LAS) has been applied to the inductivity heated oxygen plasma and the accurate measurement of the translational temperature has been successful. 3 In our laboratory, cavity enhanced absorption spectroscopy (CEAS) has been applied for the arc heated flow diagnostics and the sensitivity has been enhanced by three orders. 4 However, in LAS and CEAS, the absorption signal is a lineintegrated value along the laser path so the Abel conversion is needed to get spatially resolved translational temperature of plasma.…”

Thermal Efficiency of Laser Driven Inductively Coupled Plasma Generator Flows

“…9) On the other hand, inductively coupled plasma (ICP) generators have garnered much attention. [10][11][12][13] The ICP generators have no electrode. They can produce an ideal test condition for TPS tests because they have no undesirable chemical reactions that result from erosion.…”

Operation Characteristics of Laser Driven Plasma Wind Tunnel

“…The wavelength is 10.6 m. The maximum output power is 2 kW and the transverse mode of the laser beam is TEM 10 . The beam divergence is less than 2 mrad at the laser exit.…”

“…[9][10][11][12] Such generators have no electrode. They can produce an ideal test condition for TPS tests because they have no undesirable chemical reactions that result from erosion.…”