Jens Osterholz

Generation of Mie size microdroplet aerosols with applications in laser-driven fusion experiments

We have developed a tunable source of Mie scale microdroplet aerosols that can be used for the generation of energetic ions. To demonstrate this potential, a terawatt Ti:Al2O3 laser focused to 2 x 10(19) W/cm2 was used to irradiate heavy water (D2O) aerosols composed of micron-scale droplets. Energetic deuterium ions, which were generated in the laser-droplet interaction, produced deuterium-deuterium fusion with approximately 2 x 10(3) fusion neutrons measured per joule of incident laser energy.

Controlled reproducible alignment of cone targets and mitigation of preplasma in high intensity laser interactions

The use of cone targets in high intensity laser-plasma experiments has been of recent interest because of their potential use in integrated fast ignition experiments. Simpler experiments provide a good avenue for understanding the underlying physics, however precise control of the alignment along with good pointing accuracy is of crucial importance. While on big laser facilities target alignment is done precisely with several microscopes, it is not always the case on smaller facilities. This can have a detrimental effect on the quality of the results. We have developed and characterized a method for accurate alignment of intense laser pulses into a cone target. This, along with optimal positioning of the focus compared to the tip, efficiently uses the shape of the target to microfocus the laser light and concentrates the hot electrons in the tip, and can mitigate preplasma issues.

Study of hot electron transport in foil, wedge, and cone targets irradiated with ultraintense laser pulses

We investigate hot electron transport in foil, wedge, and cone targets irradiated with ultraintense femtosecond laser pulses by observing the transition radiation emitted from the targets rear side. Two-dimensional images and spectra of coherent transition radiation along with x-ray detection have revealed the spatial, temporal, and temperature characteristics of hot electron micropulses. Various patterns from different target and laser configurations suggest that hot electrons were guided by the strong static electromagnetic fields at the target boundary.

Study of hot electron transportation in foils and wedge targets irradiated with ultrashort laser pulses

We investigated the hot electron transport in foil and wedge shaped targets irradiated with ultra-intense laser pulses. The results suggest that the electrons are guided by the strong quasi-static electromagnetic fields at the wedge boundary.