No abstract

No abstract

No abstract

No abstract

An investigation of the luminosity structure, electron density, temperature, and arrival time of electrode material in the shock heated region of the plasma produced in a T-tube has disclosed that for the conditions studied the luminosity from this region originates primarily from gases that have passed through the contact surface. A plausible explanation for this mixing of discharge gases with shock heated gas is discussed. The proposed inertial instability of the contact front is an alternative explanation rather than radiation absorption in the gas ahead of the luminous plasma for the high values of temperature and anomalous values of electron density that have been measured in electromagnetic shock tubes by numerous workers.For high MACH numbers and an initial pressure of the order of 1 mm Hg CLOUPEAU 1 has shown that most of the luminosity in an electromagnetic Hshaped shock tube originates from the plasma produced by the driving current and not from gases that are shock heated. This conclusion is in agreement with the work of JEANMAIRE, KLINGENBERG and REI-CHENBACH 2 and of BARNARD and CORMACK 3 . CHANG 4 has shown that the distance required for dissociative equilibrium to be reached is long, typically 0.4 to 4 cm for a M25 shock passing into un-preexcited hydrogen at an initial pressure of 0.2 mm Hg.MCLEAN, FANEUFF, KOLB and GRIEM 5 have explained their much shorter observed times to reach equilibrium as being due to the absorption of radiation in the gas in front of the shock. BREDERLOW 6 has determined the position of the contact front and has observed luminosity emanating from the shockheated region in hydrogen in a T-tube. The object of the present work is to extend BREDERLOW'S investigations by making a spectroscopic study of the plasma produced under transition conditions when the gas in the shock heated region is becoming luminous. Spectroscopic methods described by GRIEM 7 and the method of determination of the source of the plasma, based on the arrival time of certain impuri-1 M.