D. Martinez, L. Waxner R. Presura Jets on a Stick University of Nevada Reno Nevada Trawatt facility Location of Authors #2 Shot #Array TypeCW diam.CW MatOW diamOW matInner diam.Outer diam. 1083*Conical N/A 15 μmAl mm19 mm 1084*Conical N/A 15 μmAl mm19 mm 1088*Conical50 μmCu15 μmAl mm19 mm 1089Conical10 μmAl μmAl mm19 mm 1092*Conical50 μmAl μmAl mm19 mm 1095CylindricalN/A 15 μmAl mm 1097Cylindrical50 μmAl μmAl mm 1100Cylindrical10 μmAl μmAl mm Conical Wire Arrays Current is split depending on the size of the inner wire Ablated plasma flows perpendicular to the wires causing the outer plasma to have a axial and radial component. The Plasma from the center wire stagnates and interacts with the outer wire plasma causing a sheared flow with a no slip boundary condition “Short Pulse” 1MA Peak, ~90ns Rise Time “Long Pulse” 0.6MA Peak, ~200ns Rise Time Marx Charged to 85 kV 100 kV Stored Energy 150 kJ 200 kJ Marx Capacitor Bank Load / Vacuum Chamber Water Gaps Gas Switch Pulse Forming Line Intermediate Storage Diagnostics: Why We Care Stabilization of current carrying plasma To support theoretical work on sheared flow To better understand the formation of stars As seen in these images, Astrophysical jet remain collimated over distances much larger than there radii. Current theories suggest that these jet are self collimated by magnetic fields [1,2,3] which as we know from Z-pinch experiments is normally unstable. Conical wire arrays allow us to look at the start of a plasma jet. Laser diagnostics X-ray diagnostics Pinhole images We used a time gated pinhole camera in addition a time integrated pinhole camera to observe the “hotspots” in the plasma. Schlieren Image typeCh1Ch2Ch3Ch1 delayCh2 delay Delay from first frame+0ns+2.19ns+3.88ns+6.63ns+8.82ns PCD Looking at the x-ray emission from the wire arrays. In these shots we observed spikes in the x-ray emission corresponding to the a localized pinch or the explosion of the center wire. Wire Array Configurations Used Zebra The laser diagnostics include Faraday, Shadow and Interferometry. We use these diagnostics to observe the collimation of the plasma at different points in time. Experiment Setup Results Copper center wire Al 5056 Center wire Without a center wire Shot 1083 Frame #1 0ns Frame #2 6.2ns Frame #3 12.4ns Frame #4 18.8ns Frame #5 25.0ns Frame #6 30.8ns 2s d 1084 Conical shock Small kinking structure is forming in the plasma jet We see a bright center surrounded by a plasma shell which we think is the center wire exploding and the wire array imploding Ch 2 Ch 1 Ch 3 The conical shock is easily seen from the shadow images This instability that has formed on the inside of the conical shock looks like Kevin Helmholtz instability. In only 7ns we can see that the instability has grown at an alarming rate. A conical shock is formed from the incoming plasma. Once plasma passes this boundary the velocity profile becomes axial dominated[4]. Shot 1084 Conclusions References Future work Again we see the center wire exploding In the current state of research we can see that shear flow does help stabilize the plasma. The center wire plays an important role of the formation of the precursor plasma but does not contribute to the stabilization of the plasma due to its early explosion. The use of Aluminum wires has shown some unusual results that needs to be further investigated. As for temperature of the plasma we do find that the conical wire arrays with a center wire do produce more energy than ones without. Currently we are working on futher anylizing the data obtained form this series of shots by looking at the plasma temperature for ratios in the spectra lines. In future experiemnts we plane to use a high resolution spectrometer to observe the doppler shift in the jet to help detriment the outside shear flow. *discussed in detail in the results section In this set of experiments we chose our arrays to investigate the various parameters that might play a role in the sheared flow of plasma. In this poster we are focusing on the difference from a conical wire array with a central wire and without. We also looked at the effects from a center wire made of different materials. We can see instablites