Artificial voids in nanodusty plasmas at high Havnes parameter

Artificial voids are an interesting and frequently studied phenomenon in dusty plasmas [E. Thomas POP 2004, M. Klindworth RSE 2007, O. Arp PRE 2011, M. Schwabe NJP 2017]. Voids are created by projectiles shot into the dust cloud or by electrostatic probes. We present investigations of artificial voids created by electrostatic probes in nanodusty plasmas at high electron depletion (Havnes parameter >>1). Nanodusty plasmas are created by using a reactive argon acetylene plasma as a particle source. After switching off the acetylene a pristine nanodusty plasma of electrons, ions, and dust particles is created, the time of the acetylene flow determines the radius of the created dust particles. By variation of the probe voltage, the size of the void can be varied. As long as the probe void has not closed, a simple force balance explains the linear increase of the void radius for probe bias variations (dust repelling regime). However, the closure of the probe void destabilizes the whole nanodust cloud and strong dust streaming and the closure of the "natural" void are observed. The ability to use the force model to estimate the plasma potential and the consequences for credible Langmuir probe measurements in nanodusty plasmas at high Havnes Parameters will be discussed (see video https://youtu.be/Nmz2nR8uTrE or search youtube for "nanodustcloud").