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Volume 80, Issue 4, April 2009
We present data from the Floating Potential Measurement Unit (FPMU) that is deployed on the starboard truss of the International Space Station. The FPMU is a suite of instruments capable of redundant measurements of various plasma parameters. The instrument suite consists of a floating potential probe, a wide-sweeping spherical Langmuir probe, a narrow-sweeping cylindrical Langmuir probe, and a plasma impedance probe. This paper gives a brief overview of the instrumentation and the received data quality, and then presents the algorithm used to reduce curves to plasma parameters. Several hours of data are presented from August 5, 2006 and March 3, 2007. The FPMU derived plasma density and temperatures are compared with the International Reference Ionosphere (IRI) and Utah State University-Global Assimilation of IonosphericMeasurement (USU-GAIM) models. Our results show that the derived in situ density matches the USU-GAIM model better than the IRI, and the derived in situtemperatures are comparable to the average temperatures given by the IRI.
Comment on “Generation of cold low divergent atomic beam of indium by laser ablation” [Rev. Sci. Instrum.76, 113302 (2005)]80(2009); http://dx.doi.org/10.1063/1.3100177View Description Hide Description
We present measurements of the velocity distribution of calcium atoms in an atomic beam generated using a dual-stage laser back-ablation apparatus. Distributions are measured using a velocity selective Doppler time-of-flight technique. They are Boltzmann-like with rms velocities corresponding to temperatures above the melting point for calcium. Contrary to a recent report in the literature, this method does not generate a subthermal atomic beam.