The new attosecond measurement system AS-1. A commercial Ti:sapphire laser (Femtopower Pro) delivers waveform-controlled few-cycle, 5-fs red (750-nm) laser pulses at a repetition rate of 4 kHz. The laser pulses produce isolated several-hundred-attosecond extreme ultraviolet pulses in the first (smaller) vacuum chamber. In the second (larger) chamber both beams - the red few-cycle laser pulse and the (invisible) extreme ultraviolet attosecond pulse - are used for real-time observation of hitherto unaccessibly rapid electron motion inside atoms, molecules, and solids. AS-1 allowed the firs real-time observation of electron tunneling out of atoms.

The high-field experimental area outside the radiation protection bunker in an early and recent phase of its construction. The experimental work stations are shown are being used for high-power attosecond pulse generation from solid surfaces, for ion acceleration and for time-resolved X-ray diffraction experiments.

The vacuum chamber for electron acceleration in a capillary discharge waveguide. The laser arrives from above the right chamber and is focussed into the middle chamber, where the capillary is located. The left part of the chamber contains diagonstics for both the electron and the transmitted laser beams.

Gas-filled capillary discharge waveguide. By firing the discharge a plasma channel is created inside the capillary in which guiding of the laser beam and/or electron acceleration can take place.

Double experimental chamber for Gigaelectronvolt-scale electron acceleration in a capillary discharge waveguide with multi-10-TW laser pulses. The laser pulse enters the right chamber, from where it is focused into the small chamber in the middle housing the capillary waveguide. Electrons and laser light then propagate to the left chamber, where both electron and laser diagnostics are located. The experimental work station is located in a radiation protection area surrounded by 1-m-thick concrete walls. Double experimental chamber for Gigaelectronvolt-scale electron acceleration in a capillary discharge waveguide with multi-10-TW laser pulses. The laser pulse enters the right chamber, from where it is focused into the small chamber in the middle housing the capillary waveguide. Electrons and laser light then propagate to the left chamber, where both electron and laser diagnostics are located. The experimental work station is located in a radiation protection area surrounded by 1-m-thick concrete walls.

Light wave sythesizer 10 (LWS-10). LWS-10 is a 10 TW sub-10-fs light source based on the novel optical parametric chirped pulse amplification (OPCPA) technique. OPCPA provides higher gain and much broader bandwidth and so much shorter pulses than conventional lasers. A weak seed laser pulse originating from a commercial 1 kHz rep. rate laser system is temporally stretched to 40 ps and parametrically amplified in two consecutive non-linear optical crystals. During this amplification process the energy of an 80 ps long pump laser is transferred to the seed and the unrequired idler. Afterwards the amplified seed is compressed temporally to 8-9 fs.

The first and second amplifier stages of LWS-10.

The Femtopower Compact Pro front-end of the LWS-10 system. This conventional kHz laser with a gas filled hollow-core-fiber for pulse bandwidth broadening provides seed pulses with 300-400 microJ energy for the optical parametric amplification. This front-end allows extreme small amount of undesired background light before the main pulse. LWS-10 has 8 orders-of-magnitude contrast in +-40 ps temporal window and there is no pedestal outside of this range.

The vacuum chamber, where the laser-driven bubble electron acceleration in gas jets takes place. On the computer screen in the front a typical quasi mono-energetic electron spectrum at 20 MeV electron energy is shown.

Inside of the electron acceleration vacuum chamber, where electrons are generated. A paraboloid mirror focusing the laser down to a few micrometer onto the gas jet, which is transversally characterized. The laser intensity is high enough that the gas is ionized and the generated electrons oscillate with near the speed of light. The light pressure of the laser pushes the electrons away and so generates a strongly non-linear plasma wave, a so called bubble, a small volume without electrons containing only ions and having extreme large elecric fields. This electric field in the bubble accelerates trapped electrons to ultra-relativistic energies.

The specially designed nozzle. Source of the high density gas jet, in which the laser produces a plasma wave that accelerates the electrons.

Inside of the electron acceleration vacuum chamber, where electrons are characterized. A scintillating screen indicates the angular distribution and divergence of the electrons. An integrating current transformer, sort of coil, is used to determine the charge of the electron bunches. Plastic and lead shields are used to filter undesirable particles and radiation. The electron energy spectrum up to 400 MeV is measured by a permanent magnet electron spectrometer.

The undulator consists of an arrangement of magnets with alternating orientation which forces the electrons onto a sinusoidal trajectory. Due to the acceleration along this path, the electrons emit spontaneous undulator radiation into a narrow cone in forward direction. Due to the relativistic energies of the laser-driven electrons in our experiment, this radiation lies in the spectral range of soft x-rays.

The detachment of electrons from carbon monoxide molecules by femtosecond laser pulses leads to a characteristic angular distribution of the molecular ions and their fragments. The angular distribution resembles the structure of orbitals from which electrons have been ionized. A detector allows the measurement of this angular distribution. The number of observed ions is displayed in color. Red and yellow indicate a high density and blue a low. copyright: mk