Production of a keV x-ray beam from synchrotron radiation in relativistic laser-plasma interaction.

We demonstrate that a beam of x-ray radiation can be generated by simply focusing a single high-intensity laser pulse into a gas jet. A millimeter-scale laser-produced plasma creates, accelerates, and wiggles an ultrashort and relativistic electron bunch. As they propagate in the ion channel produced in the wake of the laser pulse, the accelerated electrons undergo betatron oscillations, generating a femtosecond pulse of synchrotron radiation, which has keV energy and lies within a narrow (50 mrad) cone angle.

Practicability of protontherapy using compact laser systems.

Protontherapy is a well-established approach to treat cancer due to the favorable ballistic properties of proton beams. Nevertheless, this treatment is today only possible with large scale accelerator facilities which are very difficult to install at existing hospitals. In this article we report on a new approach for proton acceleration up to energies within the therapeutic window between 60 and 200 MeV by using modern, high intensity and compact laser systems. By focusing such laser beams onto thin foils we obtained on target intensities of 6 x 10(19) W/cm2, which is sufficient to produce a well-collimated proton beam with an energy of up to 10 MeV. These results are in agreement with numerical simulations and indicate that proton energies within the therapeutic window should be obtained in the very near future using such economical and very compact laser systems. Hence, this approach could revolutionize cancer treatment by bringing the "lab to the hospital-rather than the hospital to the lab".

Enhancement of high-order harmonic generation at tuned wavelengths through adaptive control.

An adaptive learning loop enhances the efficiency and tuning of high-order harmonic generation. In comparison with simple chirp tuning, we observe a broader tuning range and a twofold to threefold enhancement in integrated photon flux in the cutoff region. The driving pulse temporal phase varies significantly for different tunings and is more complicated than a simple chirp. We compare our experimental results with a one-dimensional, time-dependent model that incorporates the intrinsic atomic response, the experimental pulse temporal phase, ionization effects, and transverse coherence of the spatial mode of the laser. The model agrees with our experimental results and indicates that a specific quantum path coupled with ionization effects determines the optimized harmonic spectrum.