The block diagram below shows the basic structure of Astra, from the source oscillator to the two target areas. Click on the boxes for further details of each section.
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The Astra system, in common with other high-power lasers, has a MOPA (Master Oscillator - Power Amplifier) architecture. In addition, because the source pulses are so short, it uses the technique of Chirped Pulse Amplification to avoid distortion of the pulses and damage to the laser during amplification.
Single pulses from the oscillator, of 12 fs duration and energy 3 nJ, are stretched to 530 ps, then amplified in the pre-amplifier to an energy of 1 mJ. After spatial filtering to clean up the beam profile, the energy is increased to 200 mJ in the second power amplifier.
At this point some of the pulse is split off and sent to the Terawatt Target Area, TA1, for use in experiments. The other half is amplified further in the third power amplifier, where it reaches pulse energies up to 1.5 Joules. The output from this amplifier is used for plasma physics experiments in the Multi-Terawatt Target Area, TA2.
In each target area, the pulses are recompressed to a duration of about 40 fs before use. Pulses are available at 10 Hz in TA1 and up to 2 Hz in TA2. TA1 also recives a pulses with a repetition rate of approximately 1 kHz, with 0.5mJ per pulse, these can be compressed to 30fs.
Click here to go to main astra photo page
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