Oe. Hankins et al., OBSERVATIONS OF VISIBLE-LIGHT EMISSION FROM INTERACTIONS BETWEEN AN ELECTROTHERMAL PLASMA AND A PROPELLANT, IEEE transactions on magnetics, 33(1), 1997, pp. 295-298
A set of experiments has been conducted on the experimental plasma-pro
pellant interaction facility PIPE to measure the burn rates of JA2 sol
id propellant as it function of plasma impingement angle with respect
to the propellant surface. The propellant test stand is designed such
that the angle of plasma impact on the propellant surface can be varie
d 0 to 90 degrees. Optical emission spectroscopy measurements were tak
en during these shots. Fiber optics were situated in two places, one c
loser to the plasma source and the second at the propellant's rear edg
e near the point of impact of plasma and propellant. The fiber optics
are connected to an optical multichannel analyzer set to observe neutr
al copper lines and molecular C-2 Swan Bands in the 505-585 nm spectra
l region. Time-averaged core arc temperatures of 8,800 to 14,000 K and
plasma densities of 2 x 10(23) to 4.5 x 10(23) m(3) have been deduced
by measurements along the axis of the device using the relative inten
sities and the Stark broadening of the copper lines. As the angle of p
lasma impact with the propellant surface increases from 0 to 90 degree
s, the overall radiant emission increases, falls and increases. Howeve
r, the measured plasma temperature decreases gradually and plasma dens
ity falls by nearly a factor of two before increasing substantially at
90 degrees. Comparisons with the measured burn rates of the JA2 prope
llent versus inclination angle suggests a stronger correlation of plas
ma burn rate with plasma kinetic energy than with the radiative heat f
lux.