Dusty plasmas have been
the fastest growing subfield of plasma physics in the last two decades. Plasma
or dust crystals are formed when the electrostatic coupling between grains is
dominant. Plasma crystals resemble condensed matter at macroscopic level and
exhibit unusual properties. We propose to carry out a novel experimental study
on the interaction of plasma flows with dust crystals. Some of the questions
that this project is aiming to elucidate are as follows. Will the plasma crystal
preserve its 3-D structure and be carried by the plasma flow? How will a
plasma-flow-dragged crystal or dust cloud interact with another plasma crystal?
This project will address topics of utmost interest and actuality related to the
plasma drag force exerted on dust grains, the potential around dust grains
immersed in a plasma flow, collective effects due to dust-dust interactions, and
propagation of ion-flow induced dust waves.
The main parts of the
experimental set-up which will be designed and built in the first phase of the
project include a coaxial plasma gun and a small size (~40 L) vacuum container
provided with 2 parallel plate-electrodes. The plasma flow will be produced in a
small coaxial gun by applying voltages of a few kVolts and currents no higher
than a few kAmps. The plasma flow speed will be ~10 km/s. An rf plasma produced
at low pressure between the parallel-plate electrodes will allow the formation
of plasma crystals consisting of micron-size spherical grains, made of different
materials such as plastic or carbon, in the sheath of the lower electrode. The
electric force due to the sheath electric field will compensate for the
microparticles’ weight and sustain them in equilibrium above the electrode. The
coaxial gun will be attached sideway to the vacuum container such that the
ejected plasma flow will be directed towards the plasma crystal.