Measurements of the effectiveZof a plasma produced in a coaxial electromagnetic shock tube (ne≈2×1016cm−3,Te≈10 eV,Ti≈300 eV) were made in both deuterium and helium gas. A fast, Ge: In photodetector (4°K) was used to measure the total infrared emission spectrum (20–100 &mgr;m) and a laser interferometer was used to measure electron density. In helium, electron temperatures were measured by line emission intensity ratios; Thomson scattering was used to measureTein deuterium. After extensive discharge cleaning (approximately 100 shots) the emission from the plasma was found to agree with the standard theory of bremsstrahlung [j&ohgr; d&ohgr; ∝ (ne2⟨Z⟩/T1/2e)d&ohgr;] with ⟨Z⟩ =2.2±0.9 for deuterium and ⟨Z⟩=4.7±2.2 for helium. The infrared detector was calibrated absolutely using a CO2laser at 10.6 &mgr;m and a relative response curve. Specific types of impurities present were identified by spectral line emission in the visible region and analysis using mass spectrometry.