PECVD

A self-consistent fluid model has been successfully developed and employed to model an electron cyclotron resonance driven hydrogen plasma at low pressure. This model has enabled key insights to be made on the mutual interaction of microwave propagation, power density, plasma generation, and species transport at conditions where the critical plasma density is exceeded. The model has been verified by two experimental methods.

Absolute ground state atomic hydrogen densities were measured, by utilisation of two-photon absorption laser induced fluorescence (TALIF), in a low pressure electron cyclotron resonance plasma as a function of nitrogen admixtures - 0 to 5000 ppm. At nitrogen admixtures of 1500 ppm and higher the spectral distribution of the fluorescence changes from a single Gaussian to a double Gaussian distribution; this is due to a separate, nascent, contribution arising from the photolysis of an ammonia molecule.

A time-dependent, spatially one-dimensional fluid-Poisson model has been applied to analyse the impact of small amounts of tetramethylsilane (TMS) on the discharge characteristics of an atmospheric-pressure dielectric barrier discharge (DBD) in argon. Based on an established argon kinetics, it includes a reaction kinetics for TMS, which has been validated by measurements of the ignition voltage at the frequency f = 86.2 kHz for TMS amounts of up to 200 ppm.

The plasma parameters of a large-area dielectric barrier discharge (DBD) in argon-HMDSO mixtures containing up to about 1600 ppm of the monomer are investigated by means of numerical modelling. A time-dependent,
spatially one-dimensional fluid model is applied, taking into account the spatial variation of the discharge plasma between plane-parallel dielectrics covering the electrodes. The dataset contains values of power dissipated in the DBD as well as the space- and period-averaged density and mean energy of the electrons as a function of HMDSO admixture.

The HelixJet (https://www.inptdat.de/helixjet) was applied to simultaneous melting and plasma treatment of polyamide (PA 12) microparticles (diameter 60 µm) used conventionally for 3D printing by laser sintering. This proof-of-principle experiment demonstrated that gaussian thickness profiles of PA 12 can be printed using the HelixJet with a rapid rate of 200 mg/s (peak growth 2 mm/s) and with advantageous material properties. The key element of this novel process is the self-regulated balance between material melting and plasma quenching.

The self-organized behaviour (locked mode) of filaments in the non-thermal atmospheric pressure plasma jet (ntAPPJ) couples a spatial patterning of the discharge (helical symmetry) and a regular motion (steady rotation). The dataset represents the mean rotation frequency of filaments in the capillary with a diameter of 4 mm and the corresponding geometric characteristics: helicality and/or filament inclination angles were measured along with the gas temperature under varying discharge conditions (electric power and argon flow rate).