The system architecture is based on chirped amplification (CPA) in several successive stages of optical parametric amplifiers, followed by direct amplification in two types of Nd:glass laser discs. Innovative technologies including disc liquid cooling enable to operate the system at the repetition rate of up to 1 shot per minute, which is more than one order of magnitude higher compared to other present-day kJ-class lasers. The laser was built by the consortium of National Energetics (USA) and EKSPLA (Lithuania), with major contribution of ELI Beamlines, which developed the 10 PW compressor and participated in development of numerous subsystems including the OPCPA preamplifiers, diagnostics or integrated electronic control system.
The L4 ATON laser pulses will be routed to E3, E4 and E5 experimental halls, where they will be used, for example, for the laser-matter interaction research or particle acceleration.
L4 ATON operating modes
The L4 laser system can operate in two main regimes as shown schematically in the block diagram below.
In the first regime, femtosecond pulses from a broadband oscillator seed the entire amplification chain consisting of OPCPA preamplifiers and flashlamp-pumped Nd:glass power amplifiers. The pulses are then compressed to reach maximum power of 10 PW in the compressor using large-aperture multilayer dielectric diffraction gratings.
In the second regime, amplified femtosecond pulses are routed into the auxiliary 1 PW compressor already after the Power Amplifier 1. Pulses generated in a separate long pulse front end are directly injected in the Power amplifier 2 instead. In this hybrid operating mode the laser simultaneously delivers PW-class femtosecond pulses and nanosecond pulses with energy of 1.2 kJ.
L4 beam line parameters
| Designed parameters | Actual Parameters (2019) | |
| Short-pulse operation of the main beam line | ||
| Peak power | 10 PW | |
| Output pulse energy | 1.5 kJ | >1.5 kJ (not compressed) |
| Pulse duration | 150 fs | |
| Repetition rate | 1 shot per minute | 1 shot per minute |
| Central wavelength | 1057 nm +/-3 nm | 1060 nm |
| Beam size (square superGaussian profile) | <625×625 mm | |
| Output laser beam pointing stability | <10 µrad RMS | |
| Output pulse external synchronization relative to the facility clock | <20 ps to RF clock with any delay relative to facility clock | |
| Laser control system | Labview and EPICS | |
| Pump laser technology | flashlamp-pumped Nd:glass amplifiers with OPCPA preamplifiers | |
| Long-pulse operation of the main beam line | ||
| Output pulse energy | 1.2 kJ | 1.2 kJ |
| Pulse duration | 0.5-5 ns (adjustable) | 0.5-10 ns (adjustable) |
| Repetition rate | 1 shot per minute | 1 shot per minute |
| Central wavelength | 1053 nm | 1053 nm |
| Auxiliary 1 PW beam line | ||
| Output pulse energy | 150 J | |
| Pulse duration | 150 fs | |
| Repetition rate | 1 shot per minute | |
L4 ATON Compressor
Length: 18 m
Height 4,5 m
Width 3,6m
Weight 55 tons
Manufactured by Streicher, Czech republic
L4 RESEARCH TEAM
References: Dr. Bedrich Rus, bedrich.rus@eli-beams.eu
