Table 1. Numerically computed peak fluence at selected locations along the beam path for (i) the current LCLS status, (ii) after completion of an overall upgrade of the LCLS mirrors, and (iii) for the ideal case of perfectly figured and infinitely long mirrors.
The current transport mirrors are responsible for binning the integrated pulse intensity in two separate lobes yielding a peak fluence (0.49 mJ mm−2) that is actually higher than that one would obtain in the ideal scenario of perfect mirrors (0.29 mJ mm−2). For the ideal case we also provide (in parentheses) the peak fluence one would obtain with perfectly figured finite-length mirrors (950 mm long). The finite size of the KB optics would be mainly responsible for the loss of peak fluence at focus.
| Peak fluence | |||
|---|---|---|---|
| Beam location | Current | After upgrade (estimated) | Ideal |
| FEH entrance aperture (mJ mm−2) | 0.49 | 0.29 | 0.29 (0.29) |
| 1 µm focal plane (mJ µm−2) | 0.20 | 4.20 | 7.70 (4.4) |
| 0.1 µm focal plane (mJ µm−2) | 18.1 | – | 589.4 (331.3) |