Development and characterization of high-frequency sources for supersonic beams of fluorine radicals

TL;DR

This study compares two high-frequency electric-discharge sources for producing supersonic fluorine radical beams, highlighting differences in efficiency and temperature of the radicals generated.

Contribution

It introduces and characterizes two corrosion-resistant discharge sources for fluorine radicals, providing detailed comparison data and optimization methods.

Findings

Plate discharge is 8-9 times more efficient in F₂ dissociation than DBD.

DBD produces internally colder fluorine radicals.

Both sources operate effectively at high pressures and repetition rates.

Abstract

We present and compare two high-pressure, high-frequency electric-discharge sources for the generation of supersonic beams of fluorine radicals. The sources are based on dielectric-barrier-discharge (DBD) and plate-discharge units attached to a pulsed solenoid valve. The corrosion-resistant discharge sources were operated with fluorine gas seeded in helium up to backing pressures as high as 30 bar. We employed a (3+1) resonance-enhanced multiphoton ionization combined with velocity-map imaging for the optimization, characterization and comparison of the fluorine beams. Additionally, universal femtosecond-laser-ionization detection was used for the characterization of the discharge sources at experimental repetition rates up to 200 Hz. Our results show that the plate discharge is more efficient in F$_{2}$ dissociation than the DBD by a factor of 8-9, whereas the DBD produces internally colder fluorine radicals.