Aerosol dielectric coatings found to significantly reduce effects of ablation on metallic surfaces
Aerosol dielectric coatings found to significantly reduce effects of ablation on metallic surfaces lead image
Magnetic compression of metal is used in a wide range of experiments, including studying nuclear fusion, material properties, and radiation sciences. The strong electrical currents used in such pulsed-power-driven experiments, however, can cause ablation of the surface of the metals, leading to asymmetric currents and non-uniform magnetic pressures that affect compression. New research provides an elegant way to limit the negative effects of metallic ablation.
Researchers in a collaboration between the University of Rochester and the University of Michigan have demonstrated a technique for significantly reducing the expansion of ablated materials on metallic surfaces by applying an aerosol dielectric coating.
Evans et al. found that coating the current carrying surfaces with a 30- to 60-micron layer of polyurethane reduced ablation expansion by a factor of two and eliminated material ejections from sharp corners. Such an approach allowed for homogenous warm dense matter samples to be magnetically compressed using currents up to 400 kA on the Michigan Accelerator for Inductive Z-Pinch Experiments (MAIZE).
Authors Matt Evans, Ryan McBride and Pierre Gourdain note the approach is relatively cheap and straightforward to implement. Polyurethane is sold at most hardware stores, and using a spray can easily coat irregular electrodes and target surfaces.
“Electrically insulating coatings have been found to help mitigate surface expansion in other experiments, but the coatings have been somewhat involved to apply,” said McBride.
Gourdain added, “By contrast, the aerosol technique is remarkably simple to apply — just spray it on.”
The group looks to use the technique to observe the aerosol coating’s effect on implosion and compression stability and to investigate if power transmission from the electrical energy storage capacitors to such targets can be improved.
Source: “Reduction of ablated surface expansion in pulsed-power-driven experiments using an aerosol dielectric coating,” by M. Evans, M. B. Adams, P. C. Campbell, N. M. Jordan, S. M. Miller, N. B. Ramey, R. V. Shapovalov, J. Young, I. West-Abdallah, J. M. Woolstrum, R. D. McBride, and P.-A. Gourdain, Physics of Plasmas (2019). The article can be accessed at https://doi.org/10.1063/1.5066231 .
