Rawat, Rajdeep Singh

The total current I_total waveform in a plasma focus discharge is the most commonly measured quantity, contrasting with the difficult measurement of I_pinch. However, yield laws should be scaled to focus pinch current I_pinch rather than the peak I_total. This paper describes how I_pinch may be computed from the I_total trace by fitting a computed current trace to the measured current trace using the Lee model. The method is applied to an experiment in which both the I_total trace and the plasma sheath current trace were measured. The result shows good agreement between the values of computed and measured I_pinch.

High energy neutrons, more than 2.45 MeV from deuteron-deuteron fusion reaction, have been measured in backward direction of plasma focus devices in many laboratories. However the experimental evidence for high energy deuterons responsible for such neutrons has not been reported so far. In this brief communication, backward high energy deuteron beam from NX2 plasma focus [M. V. Roshan et al., Phys. Lett. A 373, 851 (2009)] is reported, which was measured with a direct and unambiguous technique of nuclear activation. The relevant nuclear reaction for the target activation is ¹²C (d, n)¹³N , which has a deuteron threshold energy of 328 keV.

The precise facet modulation of transition metal nitrides (TMNs) has been regarded as an essential issue in boosting electrocatalytic H₂ production. Compared to thermal nitridation, the plasma technique serves as a favorable alternative to directly achieve TMNs, but the apparent surface heating effect during plasma treatment inevitably causes the thermally stabilized nitride formation, resulting in the deterioration of the highly reactive facet. To optimize the hydrogen evolution reaction (HER) behavior, an auxiliary cooling assisted plasma system to selectively expose Ni₃N (2-10) with favorable activity by controlling surface heating during plasma nitridation is designed. The resultant nickel nitride (cp-Ni₃N) nano-framework delivers exceptional catalytic performance, evidenced by its low overpotential of 58 and 188 mV at the current density of 10 and 100 mA cm⁻² for HER, in stark comparison with that of normal plasma and thermally fabricated Ni₃N. Operando plasma diagnostics along with numerical simulation further confirm the effect of surface heating on typical plasma parameters as well as the Ni₃N nanostructure, indicating the key factor responsible for the high-performance nitride electrocatalyst.