Infrared characterization of a cascaded arc plasma

We have constructed a cascaded are light source and characterized its infra red emission properties. Breaking down Ar gas flowing through the cascaded are channel forms a wall-stabilized plasma, The properties of the plasma ca n be adjusted by varying the pressure (1-4 atm) and the current flowing thr ough the are (15-30 A). The infrared (2000-10,000 cm(-1)) emission of the c ascade are plasma is measured using a Fourier transform infrared (FTIR) spe ctrometer, The infrared emission can be used to determine the electron dens ity (n(e)) and the temperature (T) of the plasma, assuming the plasma is in partial local thermodynamic equilibrium (PLTE). The plasmas at the highest currents and pressures satisfy the assumption of PLTE, while the plasmas a t other conditions do not. This enables the calculation of new transition p robabilities for the infrared transitions in the Ar plasma. The electron de nsity of the cascaded are Ar plasma at our operating conditions varies betw een 2 and 5 x 10(22) m(-3) while the temperature varies between 9500 and 11 ,500 K. (C) 2001 Elsevier Science Ltd. All rights reserved.