THE RESPONSE OF THE INDUCTIVELY-COUPLED ARGON PLASMA TO SOLVENT PLASMA LOAD - SPATIALLY-RESOLVED MAPS OF ELECTRON-DENSITY OBTAINED FROM THEINTENSITY OF ONE ARGON LINE
Dgj. Weir et Mw. Blades, THE RESPONSE OF THE INDUCTIVELY-COUPLED ARGON PLASMA TO SOLVENT PLASMA LOAD - SPATIALLY-RESOLVED MAPS OF ELECTRON-DENSITY OBTAINED FROM THEINTENSITY OF ONE ARGON LINE, Spectrochimica acta, Part B: Atomic spectroscopy, 49(12-14), 1994, pp. 1231-1250
A survey of spatially resolved electron number density (n(e)) in the t
ail cone of the inductively coupled argon plasma (ICAP) is presented:
all of the results of the survey have been radially inverted by numeri
cal, asymmetric Abel inversion. The survey extends over the entire vol
ume of the plasma beyond the exit of the ICAP torch; It extends over d
istances of z = 5-25 mm downstream from the induction coil, and over r
adial distances of +/- 8 mm from the discharge axis. The survey also e
xplores a range of inner argon flow rates (Q(IN)), solvent plasma load
(Q(SPL)) and r.f. power: moreover, it explores loading by water, meth
anol and chloroform. Throughout the survey, n(e) was determined from t
he intensity of one, optically thin argon line, by a method which assu
mes that the atomic state distribution function (ASDF) for argon lies
close to local thermal equilibrium (LTE). The validity of this assumpt
ion is reviewed. Also examined are the discrepancies between n(e) from
this method and n(e) from Stark broadening measurements. With the err
or taken into account, the results of the survey reveal how time avera
ged values of n(e) in the ICAP respond over an extensive, previously u
nexplored range of experimental parameters. Moreover, the spatial info
rmation lends insight into how the thermal conditions and the transpor
t of energy respond. Overall, the response may be described in terms o
f energy consumption along the axial channel and thermal pinch within
the induction region. The predominating effect depends on the solvent
plasma load, the solvent composition, the robustness of the discharge,
and the distribution of solvent material over the argon stream.