Fig. 3
Microscopy images (10\(\times\) magnification, NA 0.28, pixel size \(\sim\)1.26 µm) showing PSI crystal delivery (proposal no. 3111) in low-viscous buffers on the SPB/SFX instrument using a type JKMH-8.11 DFFN. The second X-ray pulse of the train is indicated with a red arrow. The gap generated by the first pulse (the red dotted line depicts its center) has traveled ca. 40 µm in the 887 ns between these two pulses (i.e. 1.13 MHz). The images show ca. 4 µm wide jets of PSI crystal-laden buffer (without PEG) generated with the same nozzle: (a) GDVN mode (i.e. no sheath flow running) and (b) with additional ethanol sheath flow. The applied flow rates were (a) \(Q_i=30\) µL/min and (b) \(Q_i=10\) µL/min plus \(Q_o=20\) µL/min, respectively. The helium flow rate was \(\dot{m}_g=33\) mg/min in both cases. As shown in Table 1, the increased jet length and stability comes at the expense of crystal hit rate due to a required reduction of the sample flow rate to accommodate to high repetition rate pulses.
