P2DN: A Pulsed Setup for High-Density Supersonic Plasma Expansion

ACS Earth and Space Chemistry, vol. 9, pp. 1510–1524

Abstract

We present the piezostack pulsed discharge nozzle (P 2 DN), which is a next-generation apparatus that enables the production of a pulsed supersonic plasma expansion over a wide range of densities. This system combines a slit discharge nozzle with a very high-throughput piezostack actuator (PSA), allowing for accurate control of the pressure upstream of the nozzle up to values of at least 2 bar. Such pressures are inaccessible with most of the currently available systems, in particular the widespread systems that employ solenoid valves. The strength of the piezostack stems from its very stable pulse-to-pulse mass flow even when operating at a very high backing pressure. Combined with a reservoir placed upstream of the discharge nozzle, the PSA distributes the gas uniformly along the slit axis producing a high-quality supersonic flow. The plasma expansion is thus produced in a controlled environment and is suitable for stable, long-run experiments. A homemade program (PSAjet) is presented that allows modeling the gas flow through the different parts of the P 2 DN and for predicting the reservoir pressure during a gas pulse. In addition, the resulting supersonic expansion is modeled by means of two complementary approaches: isentropic relations are employed to retrieve the thermodynamic parameters along the jet axis, while Direct Simulation Monte Carlo (DSMC) is used to reproduce the supersonic expansion complex structure. These programs are suitable for tuning the experimental parameters to reach the target conditions. The P 2 DN proved to produce higher densities of exotic carbon chain radicals that result in stronger absorption features, opening the way to the detection of new weak molecular signatures and allowing for new plasma studies and the investigation of the induced chemistry.

Authors 3

1. Nicolas Suas-David corresponding Aachen

   Leiden University · Leiden Observatory

   Affiliation as printed

   Laboratory for Astrophysics, Leiden Observatory

   Leiden University

2. H. Linnartz Aachen

   Leiden University · Leiden Observatory

   Affiliation as printed

   Laboratory for Astrophysics, Leiden Observatory

   Leiden University

3. Jordy Bouwman Aachen

   Leiden University · Leiden Observatory

   Affiliation as printed

   Laboratory for Astrophysics, Leiden Observatory

   Leiden University