Experimental chamber 2: Highest intensities
Experimental chamber 2: Highest intensities
We generate our highest light intensities in this chamber: The focal spot is only 2 µm large, and the intensity achieves I = 1018 W/cm2. With this intensity free electrons come close to the speed of light when they oscillate in the laser field, such that relativistic effects start playing a role. We illuminate smooth surfaces which must be moved for each laser pulse. Precise positioning is crucial because the focal spot must be exactly on the surface.
Chamber interior: You can see the focussing mirror (right, gold-coated), the target holder (with two adjusting knobs on top), and the entrance to the XUV spectrometer (left, white plate with slit). (Photo: D. Hemmers)
Our research topics:
- Absorption of the laser pulses: Which fraction of the incident light energy is transferred to matter? How does this work in detail? And how can we influence or control the absorption? For answering such questions, we examine the remaining part of the laser pulse, for example, we analyse the target after interaction and investigate the radiation emitted by the plasma.
- Plasma radiation: The generated plasma emits characteristic radiation from the visible to the hard x-ray range. This radiation contains much detailed information about the plasma properties. We employ special spectrometers for the different spectral ranges, some of them self-developed.
- Generation of surface harmonics: A part of the laser pulse is always reflected by the developing plasma. Sometimes this part contains laser-like hard radiation beside the laser light, with multiples of the laser frequency. We do experiments for understanding the generation of this radiation, and we try to optimize it.