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Papers by Ed Figura
Physics of Fluids B: Plasma Physics, 1991
A Z-pinch discharge in a quartz fiber (20–125 μm diameter) driven by a 150 kA current with a rise... more A Z-pinch discharge in a quartz fiber (20–125 μm diameter) driven by a 150 kA current with a rise time of 50 nsec has been investigated. The pinch was found to develop an m=0 instability during the time of current rise and before the whole fiber had been formed into a plasma. No anomalously stable behavior was seen. The bright spots associated with the instability expanded radially and moved in the axial direction with typical velocities of a few 106 cm sec−1. A coronal plasma was found to exist with density 1016 cm−3 at a radius 500 μm. There was evidence of an energetic (20 keV) electron beam. The observed plasma expansion and ionization agreed well with a one-dimensional magnetohydrodynamic simulation. The simulation showed that the light which was observed to be generated in the core of the optical fiber was due to shock heating. The predicted temperature of the surface of the plasma was also in good agreement with an estimate of the temperature (25±8 eV) obtained by assuming th...
Shock Waves, 1992
Experimental studies have been performed on two-dimensional reactive blast waves in a diverging n... more Experimental studies have been performed on two-dimensional reactive blast waves in a diverging nozzle. Both blast and reaction wave loci have been measured and the results compared with numerical calculations. With the inclusion of additional wedges into the channel reactive Mach reflections were generated and the subsequent interactions of these waves have been observed and modelled using a full chemistry scheme. The results are in excellent agreement and the technique shows great promise for the study of the coupling between chemistry and gas dynamics under conditions similar to those obtaining within a single cell of a gaseous detonation.
IEEE Transactions on Magnetics, 1993
Ropl Ordnance arc undertaking a fundamental research programme into the internal ballistig of ele... more Ropl Ordnance arc undertaking a fundamental research programme into the internal ballistig of electrothermal chemical guns. The Tc(icIveh is separated into two inter4ependant pmgrammq numerical modelling and experimentation. The modelling separates the gun into three sectioq power supply, plasma generator and gun chambcrbarml. The latter two arc modelled using a finite ~n c e ' 111. THE CAPILLARY DISCHARGE
IEEE International Conference on Plasma Science
ABSTRACT The magnetic compression of a 3-mm-diameter aluminum vapor jet produced by foil explosio... more ABSTRACT The magnetic compression of a 3-mm-diameter aluminum vapor jet produced by foil explosion has been studied. The jet is compressed by the current of GAEL, a 2-Ω, 0.1-TW machine. The plasma is diagnosed by a double-pinhole (100-μm) camera, with one pinhole filtered by 10 μm of beryllium and the other by 800 Å of aluminum on a 6-μm Kimfol substrate. An optical streak camera shows the radial compression as a function of time. A Mach-Zehnder interferometer, operated with a dye laser at 580 nm, is synchronized with the discharge to give the aluminum plasma density at different times. Filtered X-ray diffraction (XRD) gives the time variation of the radiation, and the XRD signal can be correlated with the pinhole pictures. Density measurements at maximum current show small radial compression of the jet, but the structure of the fringes suggests density inhomogeneities along the z-axis of the column. X-ray pinhole pictures are compatible with 1-keV radiation, which corresponds to a temperature between 200 and 500 eV
Physics of Fluids B: Plasma Physics, 1991
A Z-pinch discharge in a quartz fiber (20–125 μm diameter) driven by a 150 kA current with a rise... more A Z-pinch discharge in a quartz fiber (20–125 μm diameter) driven by a 150 kA current with a rise time of 50 nsec has been investigated. The pinch was found to develop an m=0 instability during the time of current rise and before the whole fiber had been formed into a plasma. No anomalously stable behavior was seen. The bright spots associated with the instability expanded radially and moved in the axial direction with typical velocities of a few 106 cm sec−1. A coronal plasma was found to exist with density 1016 cm−3 at a radius 500 μm. There was evidence of an energetic (20 keV) electron beam. The observed plasma expansion and ionization agreed well with a one-dimensional magnetohydrodynamic simulation. The simulation showed that the light which was observed to be generated in the core of the optical fiber was due to shock heating. The predicted temperature of the surface of the plasma was also in good agreement with an estimate of the temperature (25±8 eV) obtained by assuming th...
Shock Waves, 1992
Experimental studies have been performed on two-dimensional reactive blast waves in a diverging n... more Experimental studies have been performed on two-dimensional reactive blast waves in a diverging nozzle. Both blast and reaction wave loci have been measured and the results compared with numerical calculations. With the inclusion of additional wedges into the channel reactive Mach reflections were generated and the subsequent interactions of these waves have been observed and modelled using a full chemistry scheme. The results are in excellent agreement and the technique shows great promise for the study of the coupling between chemistry and gas dynamics under conditions similar to those obtaining within a single cell of a gaseous detonation.
IEEE Transactions on Magnetics, 1993
Ropl Ordnance arc undertaking a fundamental research programme into the internal ballistig of ele... more Ropl Ordnance arc undertaking a fundamental research programme into the internal ballistig of electrothermal chemical guns. The Tc(icIveh is separated into two inter4ependant pmgrammq numerical modelling and experimentation. The modelling separates the gun into three sectioq power supply, plasma generator and gun chambcrbarml. The latter two arc modelled using a finite ~n c e ' 111. THE CAPILLARY DISCHARGE
IEEE International Conference on Plasma Science
ABSTRACT The magnetic compression of a 3-mm-diameter aluminum vapor jet produced by foil explosio... more ABSTRACT The magnetic compression of a 3-mm-diameter aluminum vapor jet produced by foil explosion has been studied. The jet is compressed by the current of GAEL, a 2-Ω, 0.1-TW machine. The plasma is diagnosed by a double-pinhole (100-μm) camera, with one pinhole filtered by 10 μm of beryllium and the other by 800 Å of aluminum on a 6-μm Kimfol substrate. An optical streak camera shows the radial compression as a function of time. A Mach-Zehnder interferometer, operated with a dye laser at 580 nm, is synchronized with the discharge to give the aluminum plasma density at different times. Filtered X-ray diffraction (XRD) gives the time variation of the radiation, and the XRD signal can be correlated with the pinhole pictures. Density measurements at maximum current show small radial compression of the jet, but the structure of the fringes suggests density inhomogeneities along the z-axis of the column. X-ray pinhole pictures are compatible with 1-keV radiation, which corresponds to a temperature between 200 and 500 eV