EUV Plasma Processes

Group leaders: Dr. Oscar Versolato / Prof. dr. Ronnie Hoekstra / Prof. dr. Wim Ubachs

Research activities

Laser produced plasma (the bright light in the center of the picture) produced by exploding a micro-droplet of molten tin using high-power pulsed laser light. We saw first plasma in our labs in February 2015! Picture courtesy of Dmitry Kurilovich.

The core expertise and interests of the EUV Plasma Processes group are in the physics of EUV-light-generating laser-produced plasma. The group employs a tin microdroplet generator to provide targets for ARCNL’s high-energy pulsed solid-state laser systems which generate a hot and very dense plasma from them. The group studies this plasma at the fundamental level: that of electrons, ions, atoms, and molecules. Active and passive spectroscopic tools covering optical, deep-ultraviolet, and EUV domains, probe plasma temperature and density, its tin charge state distribution, effects of self-absorption, and the line- and continuum emission of the EUV light in all its aspects. Plasma pressure, and its impact, is sensitively studied by probing the propulsion and fluid-dynamic deformation of the laser-targeted microdroplet, from the incompressible to compressible regimes, using “high-speed” shadowgraphy systems. Detailed studies of the formation and ejection of fast ionic and neutral particulates by the plasma provides a detailed look into the plasma, and enables the study of the interaction of the plasma with its direct environment.

Interesting features in the remaining tin “debris” shooting at high speed to the left of the shadowgraph-picture (while rapidly expanding), after the generation of the laser produced plasma (the bright light on the right hand side of the picture).

Key atomic plasma processes are probed in setups dedicated to provide insights into the plasma’s microscopic physics origins at the single particle level. The group has a branch at the Zernike Institute of Advanced Materials at the University of Groningen where an electron-cyclotron ion source provides multiply charged tin ions for charge-state-resolved studies of ion-molecule and ion-surface collisions at the quantum level. Fundamental electron-ion interactions and tin’s atomic properties are investigated in a larger collaboration including the Max Planck Institute for Nuclear Physics in Heidelberg.