Simultaneous streak and frame interferometry for electron density measurements of laser produced plasmas.

A system of two collinear probe beams with different wavelengths and pulse durations was used to capture simultaneously snapshot interferograms and streaked interferograms of laser produced plasmas. The snapshots measured the two dimensional, path-integrated, electron density on a charge-coupled device while the radial temporal evolution of a one dimensional plasma slice was recorded by a streak camera. This dual-probe combination allowed us to select plasmas that were uniform and axisymmetric along the laser direction suitable for retrieving the continuous evolution of the radial electron density of homogeneous plasmas.

Observation of self-sustaining relativistic ionization wave launched by a sheath field.

We present experimental evidence supported by simulations of a relativistic ionization wave launched into a surrounding gas by the sheath field of a plasma filament with high energy electrons. Such a filament is created by irradiating a clustering gas jet with a short pulse laser (115  fs) at a peak intensity of 5×10(17)  W/cm2. We observe an ionization wave propagating radially through the gas for about 2 ps at 0.

Heat flow diagnostics for helicon plasmas.

We present experimental studies of power balance in an argon helicon discharge. An infrared camera measures the heating of the dielectric tube containing a helicon discharge based on measurement of temperature profiles of the tube surface before and after a rf pulse. Using this diagnostic, we have measured surface heating trends at a variety of operating conditions on two helicon systems: the 10 kW VASIMR VX-50 experiment and the University of Texas at Austin 1 kW helicon experiment.

Method to estimate the electron temperature and neutral density in a plasma from spectroscopic measurements using argon atom and ion collisional-radiative models.

We present a method to infer the electron temperature in argon plasmas using a collisional-radiative model for argon ions and measurements of electron density to interpret absolutely calibrated spectroscopic measurements of argon ion (Ar II) line intensities. The neutral density, and hence the degree of ionization of this plasma, can then be estimated using argon atom (Ar I) line intensities and a collisional-radiative model for argon atoms. This method has been tested for plasmas generated on two different devices at the University of Texas at Austin: the helicon experiment and the helimak experiment.

Improving surgical services performance through changing work culture.

Children's memorial hospital administrators knew that they needed to improve their surgical services infrastructure to accommodate growing patient volume, implement new technology, and address a major shift from inpatient to outpatient surgery. The hospital partnered with an outside consultant to better understand the impact of the work environment and culture on performance and to identify opportunities for improvement. During a seven-month period, new work processes, tools, and staff training helped significantly boost surgical services volume and revenue.