  A novel method for doping plasmas in pulsed-power experiments with gaseous
elements has been developed. A fast gas valve, a nozzle, and a skimmer are used
to generate an ultrasonic gas beam that is injected into a planar-geometry
microsecond plasma-opening-switch (POS). An array of ionization probes with
relatively high spatial and temporal resolutions was developed for diagnosing
the absolute injected-gas density and its spatial profile. The properties of
the gas column were also studied using spectroscopy of line emission that
results from the interaction of the doped gas with the POS prefilled plasma.
The doped column is found to have a width of ~1 cm and a density of
(0.8-1.7)*10^14 cm-3. Observations of characteristic emission lines from the
doped atoms and their ions allow for various spectroscopic measurements, such
as the magnetic field from Zeeman splitting and the ion velocity distributions
from Doppler shifts, that are local in three dimensions. It is shown that this
gas doping technique can also be used to study proton-dominated plasmas that
cannot be studied with simple emission spectroscopy due to the lack of light
emitting ions. The variety of gases used with this method, together with the
small valve dimensions and its fast opening, make it potentially useful for
broad diagnostics of various short-duration plasma experiments.
