Fig. 1. Block diagram of Weizmann Institute of Science (WIS) laser system. Pump units are shown in green.

Fig. 2. (a) Photograph of WIS laser system. (b) Deformable mirror for one of the beams. (c) Ceramic diffuser used as a pulse selector.

Fig. 3. (a) Interior of compressor chamber, with a sketch depicting the path of one of the two IR beams. The uncompressed beam (orange in the image) enters near (1) and reflects off the tops of the first and second gratings (2 and 3, respectively), becoming spatially chirped (rainbow pattern). It is shifted vertically down by the periscope (4), reflects off the bottoms of the second and first gratings (3 and 2, respectively), thereby completing the compression (red in the image). Most of the beam (5) is sent to the experimental chamber, and a small part is leaked (6) and sent to the diagnostics bench. The second high-power beam traverses a similar path in the left half of the compressor chamber. (b) Compressor (front, round) and deformable mirror (rear, square) chambers inside the clean room. For scale, the external diameter of the compressor chamber is ∼1.7 m.

Fig. 4. General view of experimental hall showing the target chambers: electron/x-ray-beam chamber (left); ion-beam chamber (right).

Fig. 5. Simplified setup of alignment (red) laser and relationship with main (IR) laser.

Fig. 6. Focal spots of red alignment and main IR laser beams: (a) measured and (b) simulated red (660 nm) focal spots with f/25; (c) measured and (d) simulated main IR laser focal spots with f/17.

Fig. 7. Focal-spot stability over 100 consecutive shots: (a) peak intensity fluctuations vs shot number; (b) RMS deviation vs shot number.

Fig. 8. Self-referenced spectral interference and third-order autocorrelator measurements: (a) measured spectral intensity and phase with (b) temporal reconstruction of pulse intensity; (c) laser contrast plotted on logarithmic scale.

Fig. 9. Measured gas density profile using a 0.5–3 mm converging–diverging supersonic nozzle with a backing pressure of 10 bars: (a) Abel-inverted gas density profile showing inversion from both sides of the symmetry axis; (b) gas density profile as a function of position along the laser axis 1 mm above the nozzle.

Fig. 10. Twenty consecutive shots: (a) raw data on electron spectrometer; (b) averaged electron spectra (solid blue curve) with shot-to-shot stability (red shaded region); (c) averaged electron vertical divergence (solid blue curve) with shot-to-shot stability (gray shaded area).

Fig. 11. Scintillator screen image showing betatron beam (centered in red-orange area) and absorption caused by various sector-shaped Ross-filter metal foils. The elements and thicknesses used are annotated on the corresponding regions.

Fig. 12. (a) Betatron radiation spectrum reconstructed from information in Ross-filter image. The estimated critical energy is E_c = 9.7 keV, and the shaded region represents the uncertainty in this parameter, which is (8.6, 10.6) keV. (b) Plot showing for each energy value the fraction of 26 shots that had a lower critical energy than this value [empirical cumulative distribution function, (eCDF)]. Shown are the estimated E_c values of the shots (black crosses) with their error bars (blue solid lines), along with the CDF of a normal distribution with a mean value of 9.8 keV and a standard deviation of 0.65 keV (red dashed line).

Fig. 13. (a) Image of 2D scintillator intensity map in logarithmic scale. The circular bright spots are an imprint of the aluminum mask with nine different thicknesses. A complex angular energy dependence is observed. The bright top-left part is due to electrons deflected by a magnet; they exhibit a different relative intensity response. The bottom part is blocked by a thick object. The red rectangles mark two different-angle points for further analysis. The target foil itself—2 μm of Ti—is oriented at 45° to the laser. (b) Normalized intensity curves at 5° and 13° angles extracted from the image. The dashed lines are the fitted expected responses for an exponential distribution of protons. The best fit for the beam at 5° gives a cutoff energy of 14 MeV, while that at 13° gives 10 MeV, showing that the more energetic components of the beam are collimated more sharply.

Fig. 14. The ∼0.5 m long Thomson parabola spectrometer (TPS) chamber (front right) connected to the target chamber (rear left) via a ∼1 m vacuum tube. On the left side of the TPS chamber is the window for electron detection, and on its back side is the microchannel-plate detector. A 70 l/s turbo pump is placed on top of the TPS chamber, where on the optical table are shown the high-voltage power supplies and vacuum meter.

Fig. 15. (a) A typical Thomson parabola image. The target was a 5-μm stainless-steel foil that was nearly normal to the laser, and the various curves correspond to different ion species. (b) The proton energy spectrum extracted from (a), showing a cutoff energy of 9.4 ± 0.3 MeV for this shot.