The "PlasmaLab" is a possible followup experiment setup for PK3-Plus and PK-4 to perform complex plasma experiments aboard the International Space Station (ISS). The idea behind PlasmaLab is to set up a complex plasma facility that is flexible in its configuration, allows to access a parameter space several orders of magnitude larger than in earlier experiments and supports user controlled plasma manipulations that result in an active modification of the particle interaction in a complex plasma. First studies on possible configurations have been performed under the working titles IMPF (International Microgravity Plasma Facility) and IMPACT (International Multi-User Plasma Atmosheric and Cosmic Dust Twin) beginning 1999, supported by DLR and ESA.
Since the end of 2007 we started to design and investigate two possible plasma chambers and as well a novel plasma generator that can fullfill the requirements for a future PlasmaLab on the ISS. This work is performed in close collaboration with the Joint Institute for High Temperatures in Moscow (JIHT, formerly IHED). In the course of this DLR financed study we designed in 2008 the first plasma chamber which is based - as former experiments - on a cylindrical geometry. Despite the other experimental setups, however, the inner geometry of the plasma chamber can be modified by an electronically controlled positioning system. Electrodes and guard rings can be moved over a significant range even during an experiment run. The electrode system can be exchanged easily in the laboratory, too. Different kind of plasma generation methods can therefore easily be tested using for example combinations of driven parallel plate electrodes or other secondary plasma sources embedded into the movable electrode bodies. A laboratory setup with this kind of cylindrical, "flexible" plasma chamber (Zyflex- chamber), as it was built in 2008/2009, is shown in fig. 1. To test the chamber under microgravity conditions, a parabolic flight setup was built in 2009 and successfully tested during the DLR parabolic flight campaigns in September 2009 (as seen in fig. 2) and September 2011.
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Fig. 1: Experimental setup of the new PlasmaLab "Zyflex" chamber with its movable electrode and guard ring combinations (see inset). The setup also include a gas support system (left) and translation stages (in front) for the optical access to the complex plasma by illuminating lasers and observing cameras.
Fig. 2: Experiment setup with Zyflex chamber operated by Thomas Reiter, Uwe Konopka and Lisa Wörner (inset from right to left) during DLR's parabolic flight campain in September 2009.
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Fig. 3: Design sketch of the novel "Dodecahedron" plasma device. This device should allow the experimenter to actively change the interparticle forces between particles in a complex plasma in a nearly spherical symmetric environment.
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As a second plasma device a plasma chamber with spherical like geometry was proposed for this study. 2009 we started the design of this plasma chamber. It consists of twelve independently controllable electrodes, arranged in the geometry of a dodecahedron, a regular polyeder that represents a close approximation to a sphere (see fig. 3). The manufacturing of a first prototype of this novel kind of plasma chamber ("Dodecahedron" chamber) is expected to be completed early 2011. Its electrodes will be driven by a twelve channel radio frequency (rf) generator that also allow each electrode to be biased by an arbitrary static (or low frequency) voltage. This new designed rf-generator will give the experimenter the flexibility to extend the accessible plasma parameter space as well as the required interparticle force manipulation. The latter is the basis to extend the study of complex plasma towards also multi particle systems that are defined by attractive forces which are unacessible with momentary setups.
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