Particle generation in pulsed plasmas

A new pulsed coaxial plasma generator has been developed in order to allow particle generation in the quench of a propagating jet to be investigated. The related process provides an extremely transient environment which is characterized by initially high energy and charge densities, steep temperature gradients and short particle residence times. The combinations of high quench rates and high charge densities, which cannot be obtained in conventional reactors such as in flames or quasistationary plasmas, provide in fact a potential for ‘freezing’ of non-equilibrium phases and for tailoring particle characteristics by means of controlling particle–particle interactions. The pulsed plasma is characterized by determining the energy coupling, the charge density, the expansion behaviour and the evolution of temperature. Particle properties such as the primary particle size and aggregate structure are determined for various process parameters, namely the energy coupling, precursor injection and ambient pressure.