Avalanche to streamer transition in particle simulations

The avalanche-to-streamer transition is studied and illustrated in a particle model. The results are similar to those of fluid models. However, when superparticles are introduced, numerical artifacts become visible. This underscores the need of models that are hybrid in space

Particle and fluid models for streamers: comparison and spatial coupling

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Het ontsteken van gasontladingen

"When discharged through an exhausted receiver this stream often divides itself into a variety of beautiful rivulets, which are continually changing their course, uniting and dividing again in the most pleasing manner" [i]. Dézé öbservatie van Joseph Priestly uit de achttiende eeuw verhaalt over één van de eerste.experimenten met gasontladingen. Ondanks de rijke geschiedenis van het vakgebied is zelfs vandaag de dag het tijds- en plaatsafhankelijke gedrag van ontladingen nog altijd niet goed begrepen, Ietterlijk vanaf het moment van ontsteke

Striations in a low pressure RF-driven argon plasma

In experiments we observed spatially periodic modulations of the light emitted by an argon plasma in a tube of 30 cm length and 2.5 cm radius. The plasma is capacitively excited by RF electrodes positioned towards the ends of the tube. The argon pressure is approximately 2 Torr. We studied the space and phase dependence of the light emitted by the spheroidally shaped striations. Temporal phase-shifts within one striation were clearly visible. Furthermore, a simple model of the electric field modulation inside the tube was used in conjunction with a Monte Carlo model in order to study the electron kinetics in the tube. The excitation rates resulting from this model are compared with the measurements

MoModel study of DC ignition of fluorescent tubes

Breakdown in a discharge tube is investigated by means of a fluid model. The discharge tube is similar to a compact fluorescent lamp tube, containing argon at 3 Torr and mercury at a few millitorr. It was found that the minimum breakdown voltage is decreased substantially compared with a tube containing pure argon. Penning ionization of mercury via an argon metastable state plays an important role in this effect. This is illustrated for a lamp operated on a DC voltage, where significant Penning ionization takes place in the wake of the ionization front. Furthermore, contrary to what is suggested in earlier literature, the development of the surface potential of the lamp is shown to be not only determined by surface charges, but also by volume charges

Model study of DC ignition of fluorescent tubes

Breakdown in a discharge tube is investigated by means of a fluid model. The discharge tube is similar to a compact fluorescent lamp tube, contg. argon at 3 Torr and mercury at a few millitorr. It was found that the min. breakdown voltage is decreased substantially compared with a tube contg. pure argon. Penning ionization of mercury via an argon metastable state plays an important role in this effect. This is illustrated for a lamp operated on a DC voltage, where significant Penning ionization takes place in the wake of the ionization front. Furthermore, contrary to what is suggested in earlier literature, the development of the surface potential of the lamp is shown to be not only detd. by surface charges, but also by vol. charges. [on SciFinder (R)