Research Projects

Plasmas at low temperature (ranging from the cryogenic to the nanokelvin temperatures) show various unconventional phenomena, and often find themselves in the strongly coupled regime. In the past, ultracold neutral plasmas (UNPs) and dusty plasmas have been studied as strongly coupled plasmas. Among these, although UNPs offer plasmas without any additional impurities, they have certain limitations, for example, (i) their short lifetime restricts proper investigation of gas-plasma interactions, transport phenomena and thermophysical properties at equilibrium. Furthermore, (ii) the sophistication of the experimental systems, such as, use of pulsed lasers and magneto-optical traps, limits the wide spread study of such plasmas. Moreover, (iii) the spacio-temporal diagnostics of these plasmas are challenging. Therefore, in this project we propose microplasmas generated in dielectric barrier discharges (DBD) at cryogenic temperatures, referred as cryoplasmas, as an economical and steady state plasma source to achieve the strongly coupled regime. The cooling in these plasmas is achieved through collisions among gas molecules mediated by the cold walls of the experimental chamber held at cryogenic temperatures. This mechanism differs from those of UNPs where it is based upon laser (radiative) cooling. Systematic experiments will be performed in an inhouse designed doubled walled cryostat experimental system at a temperature of ~ 10 – 150 K. Although the gas temperature dependence of the plasma properties in these weakly ionized plasmas have been studied earlier, the intra-species plasma interactions which lead to such dependence lack physical insights. Therefore, in this proposed work, an atomistic approach will be employed through detailed experiments and molecular dynamics simulations, which will elucidate the roles of gas-gas, gas-surface, and gas-plasma interactions in determining the unique and interesting plasma properties. The methodical experiments and simulations are expected to build the cryoplasma system as a robust source for various low temperature applications including high precision etching, ashing, treatment of biological tissues or as an ion source for the generation of quantum beams. Therefore, it will be interesting to investigate the physics of these effects experimentally to clarify the various physical phenomena in cryoplasmas and the low temperature ion beams that can be extracted from these plasmas.