To track the time jitter between X-ray and optical lasers on a shot-to-shot basis, a real-time diagnosis using the femtosecond X-ray/optical cross-correlation technique is referred to as the time tool. The ionization of x-ray on the YAG crystal turns opaque to the optical light. In figure 1, the shadow area represents that the x-ray arrives earlier than the laser pulse. Therefore, the dashed line represents the t0 position. The old time-tool setup using the leak from the drive beam had only 5Hz rep-rate. The intensity and pulse duration were varied with drive beam.
The time tool is cross-referenced to the target plane using another YAG window at the target center position, with a small aperture temporarily inserted in the drive beam to spread the laser focus at the target plane. The time tool measures an RMS jitter of ~ 100 fs between the MEC laser and the x-ray beam.
Layout
The new time tool beam split 10% (~1mJ) from MPA 1 out. The beam path (purple line in Fig. 1)is routing along the wall of the MPA2 box, across the stretcher box, elevating from 3.5" to 5.5" in height, routing around the big compressor, through TT-shutter, and elevating from 5.5" to 28" to the second floor of the time tool/compressor/delay box( red area). The second floor contains delay switches, a compressor, manual delay stage. Then a periscope sends the beam down to the first floor, which contains a remote delay stage and final pointing mirrors to send the beam to the YAG stag inside the vacuum chamber.
Figure 1.
Layout
Figure 1.
Switch among different configurations
Configuration 1:
Configuration 2:
Configuration 3:
