Speaker
Description
The X-ray free-electron laser (FEL) FLASH in Hamburg I currently installing installing a new FLASH1 beamline incorporating external seeding using High Gain Harmonic Generation (HGHG) and Echo Enabled Harmonic Generation (EEHG). Our novel UV seed laser system matches FLASH burst operation pattern with 1 MHz pulse trains and 600 µs duration at 10 Hz (6000 pulses/sec). It features two beams: Seed 1 (343 nm, 500 fs, 50 µJ) and Seed 2 (297 nm - 317 nm tunable, 50 fs, 16 µJ), pushing the limits of average in-burst power and pulse energy in UV. The laser system is designed to meet the stability requirements for 24/7 availability at a operating user facility.
Here, we will present our seed laser design, which employs a green-pumped femtosecond Optical Parametric Chirped Pulse Amplification (OPCPA) and an highly efficient cascaded sum frequency conversion (ccSFG) along with the installation status. Additionally, we will discuss our 40-meter vacuum beam transport system and our strategies to handle beam pointing, high peak powers, specialized coatings, variable B-integral adjustments, timing stabilization and pulse compression.
