A contoured gap coaxial plasma gun with injected plasma armature

Abstract

A new coaxial plasma gun is described. The long term objective is to accelerate 100-200 microg of plasma with density above 10(17) cm(-3) to greater than 200 km/s with a Mach number above 10. Such high velocity dense plasma jets have a number of potential fusion applications, including plasma refueling, magnetized target fusion, injection of angular momentum into centrifugally confined mirrors, high energy density plasmas, and others. The approach uses symmetric injection of high density plasma into a coaxial electromagnetic accelerator having an annular gap geometry tailored to prevent formation of the blow-by instability. The injected plasma is generated by numerous (currently 32) radially oriented capillary discharges arranged uniformly around the circumference of the angled annular injection region of the accelerator. Magnetohydrodynamic modeling identified electrode profiles that can achieve the desired plasma jet parameters. The experimental hardware is described along with initial experimental results in which approximately 200 microg has been accelerated to 100 km/s in a half-scale prototype gun. Initial observations of 64 merging injector jets in a planar cylindrical testing array are presented. Density and velocity are presently limited by available peak current and injection sources. Steps to increase both the drive current and the injected plasma mass are described for next generation experiments.

Experimental characterization of a coaxial plasma accelerator for a colliding plasma experiment

“…20 The prefilled gas environment allows for a more precise and synchronized ignition of the presented plasma gun than the implementation of a gas puff valve. 21 On one hand, the accelerated plasma will now lose energy on its way due to collision processes with the neutral gas, 13 but on the other hand, there is no deposited energy inside a pinch at the end of the electrodes, like it is the case in a DPF. 8 In summary, the presented work seizes the advantages of both technologies the Marshall-type plasma gun and the DPF to generate an optimized ambient for the examination of the colliding plasmas.…”

“…9 Further applications for single plasma accelerators include x-ray lithography, laboratory modeling of astrophysical jets, and thruster for the propulsion in space and plasma refueling for fusion reactors. [10][11][12][13] Colliding plasmas were suggested for application in high energy density physics, 14 experimental applications in astrophysics, specifically galactic outflows, 3,13 and also as driver for magnetoinertial fusion. [15][16][17] Similar to a Marshall-type set-up, no magnetic field was applied in the coaxial plasma accelerator presented here.…”

Multi-chord fiber-coupled interferometer with a long coherence length laser

“…To this end, an 8 chord, visible, heterodyne, fiber-optic based interferometer has been designed and built for measuring n e during experiments on one-jet propagation and two-jet merging, as well as the merging of thirty plasma jets. Individual plasma jets, which are generated and accelerated by railguns manufactured by HyperV Technologies, 3,4 are expected to have initial density n e ≈ 10 15 − 10 17 cm −3 , temperature 1-5 eV, and velocity ≈ 50 km/s, corresponding to Mach numbers of M ≈ 10 − 35.…”

Note: On the generation of sub-300 keV flash-X-rays using rod-pinch diode: An experimental investigation

“…This mechanism of current sheet propulsion is akin to the mechanism suggested for body force development in plasma focus and pulsed plasma guns. 9 A possible, rather simple, explanation keeping above mechanism in mind is attempted here. For an unmoved current sheet a schematic representation in Figure 4 depicts the magnitude of B θ fields in proportion to circle sizes, radial current density, J r and the magnitude of axial force intensity in proportion to arrow sizes.…”