Skip to main content
eScholarship
Open Access Publications from the University of California

UC San Diego

UC San Diego Electronic Theses and Dissertations bannerUC San Diego

Investigation of coronal plasma dynamics in tungsten and carbon X-pinches

  • Author(s): Madden, Robert Edward
  • et al.
Abstract

Experiments are reported on that examine sources for investigating low density plasma (around 10̂17 electrons/ cm³). Quantitative measurements of the coronal plasma density are recovered using interferometry simultaneously with laser shadowography of the late time diode gap formation in 2- and 4-wire tungsten x-pinches using an 80 kA, 50ns current pulse are presented. Axial expansion of the gap occurs at ̃ 10⁶ cm/s for both 2- and 4-wires systems and is likely to be driven by an axial JxB force resulting from radial current flow in the plasma mini- diode 'electrodes'. Radial density profiles suggest re- pinching of the low density plasma occurs after the main pinch resulting in secondary x-ray emission peak >10ns after the first, which is recorded with a pair of pin diodes. We also report on the first investigations of the use of carbon fibers in an x-pinch load using a 250 kA linear transformer driver (LTD). Multi-frame laser shadowography is used to examine the evolution of the pinch, and shows that carbon loads demonstrate wire expansion, cross-point pinch and gap formation as observed in x-pinches constructed from high Z materials. Radiographs using the carbon x-pinch as the source and time-resolved x-ray emission measurements show that the carbon x-pinch has sufficient emission at distances >10 cm from a small hotspot in the 500 eV < hv < 3 keV range to show that the carbon x-pinch has potential as a radiographic source for diagnosing low density plasmas

Main Content
Current View