During the academic semesters the plasma physics department hosts seminars on Tuesday at 2:30 pm.
If you have questions or want to suggest a speaker/topic, please contact Prof. Olga Rosmej or Dr. Paul Neumayer.

Plasmaphysik Seminar

Status of the MEC instrument and high-resolution x-ray spectroscopy in dense plasmas with an XFELONLINE ONLY

by Dr Dimitri Khaghani (SLAC National Accelerator Laboratory)

Europe/Berlin
Online

Online

Zoom-Meeting https://gsi-fair.zoom.us/j/96629963798 Meeting-ID: 966 2996 3798 Kenncode: 130302
Description

The Matter in Extreme Conditions (MEC) instrument at the Linac Coherent Light Source (LCLS) is a user-oriented facility that combines the power of optical laser systems with the brightness of an x-ray free electron laser.

An overview of the long- and short-pulse laser systems, the x-ray beam properties and the available scientific instrumentation will be given. We will also discuss the ongoing in-house projects that are expanding the instrument’s capabilities in terms of operational reliabilities and diagnostics offer. A large-scale upgrade of the instrument has recently passed a major approval milestone. With the construction of a high-repetition PW-class laser, this project called MEC-U will dramatically increase the scientific opportunities for our user community. The latest news about MEC-U will be presented.

After an exhaustive introduction to the facility, we will dive into an example of the exceptional capabilities offered by the MEC instrument to study transient processes in dense plasmas. The MEC short-pulse laser was used to generate a dense plasma of highly charged vanadium ions. The LCLS photon energy was tuned to match the energy of specific transitions in the He-like Rydberg series. The seeded mode of the XFEL provided a narrow energy bandwidth allowing for the resonant photoexcitation of a single spectral line. Using a high-resolution x-ray focusing spectrometer and a CCD camera, we were able to observe the frequency redistribution pathways of the decaying 1s5l electronic level in a laser-driven plasma. Unexpectedly intense emission of lines above the XFEL photon energy was recorded, which is attributed to collisional excitation effects taking place conjointly with the XFEL photopumping. This method unravels complex fundamental processes acting in hot dense plasmas. It also paves the way to a time and spatial resolution of plasma conditions using self-seeded x-ray laser resonance pumping.

Zoom-Meeting
https://gsi-fair.zoom.us/j/96629963798

Meeting-ID: 966 2996 3798
Kenncode: 130302

Organized by

Olga Rosmej
Paul Neumayer