Fig. 1. Three main stages of the MagLIF concept: (left) early magnetization in which the radial magnetic field line compress then Be liner while an axially external field is applied, (middle) laser heating via a long-pulse kJ-class laser yielding plasma temperatures of order 100 eV, (right) fuel compression and fusion neutron yield due to magnetic confinement.

Fig. 2. Plot of PM spectra for $\text{MI}=2.42$ (red) and $\text{MI}=5.52$ (blue) showing how first-order sideband interference generates a 2 GHz heterodyne beat note used to generate a PM failsafe trigger. The main modulation frequency is 14.8 GHz and the reference is 12.8 GHz. The solid red sideband represents the first-order sideband transmitted by an étalon.

Fig. 3. Functional diagram of the optical assembly that generates the main PM spectrum injected into ZBL and that also generates the heterodyne signal that triggers the PM failsafe. Red lines with circles denote optical fibers. Mode matching lenses for the confocal scanning étalon, and its output collimating lens, are not shown. The étalon transmits only one first-order sideband of the reference PM spectrum.

Fig. 4. An example of a 30 ns transition time from high to ground for the PM failsafe system. A monitor output for the 2 GHz heterodyne beat note is shown in red, and the output of the 180 MHz buffer into $50~\unicode[STIX]{x03A9}$ on a 12 GHz oscilloscope is shown in blue. The transition time to a level of 1 V, approximately the trigger-inhibit threshold for an SRS DG535 delay generator equipped with an optional inhibit input, is adjustable from about 22–40 ns. Note that the 35 ns margin of safety described in the text is measured relative to the time when the falling edge of the failsafe signal crosses this 1 V threshold.

Fig. 5. The PM spectrum for the nominal value of $\text{MI}_{\text{Main}}=5.52$ and the spectra for $\text{MI}_{\text{Main}}=4.5$ and $\text{MI}_{\text{Main}}=6.2$, where the first-order sideband amplitude is diminished sufficiently to result in a PM failsafe event. All three PM spectra are plotted on the same vertical scale. Both modulation frequencies and the resulting heterodyne beat note frequency remain unchanged during these measurements.

Fig. 6. Frequency doubled laser energy versus pulsewidth.

Fig. 7. ZPW main amplifier configuration after full beam aperture upgrade. In this configuration, the top and bottom level of the amplifier contain laser glass for a total of 10 laser slabs. The full aperture beam enters the top level of the amplifier housing (top right) and wraps around to the lower level laser slabs, where it is retro-reflected by a mirror. In this way, one can preserve the same total gain of 10 amplifier slabs while cutting the pulsed power requirements in half.

Fig. 8. Schematic of the modified OPCPA system. One can see that the system can be either seeded with an SLM laser (100 pJ) or a stretched short pulse seed (375 pJ). Either pulse is amplified in the first stage by a walk-off compensated double LBO stage ($2~\text{mm}\times 25~\text{mm}$ crystals). The same technique is used for OPA stage 2 ($2~\text{mm}\times 13~\text{mm}$ crystals) with a final amplification in a single BBO crystal. The output beam has a flat-top beam size of 4 mm FWHM and 45 mJ energy at 10 Hz repetition rate.

Fig. 9. Schematic of the modified rod amplifier section. A $=$ aperture, VSF $=$ vacuum spatial filter, QWP $=$ quarter-wave plate, FI $=$ faraday isolator, PC $=$ Pockels cell.

Fig. 10. Bird’s-eye view of the Z-backlighter facility (Building 986, bottom) and the Z pulsed power facility (Building 983, top). Building 986 houses ZBL and ZPW. Both lasers can be sent (separately or co-injected) into the Target Bay for stand-alone experiments in up to four dedicated target chambers. A single beamline connects the Target Bay and the Z pulsed power facility. This beamline is currently used by ZBL only in order to provide pre-heating of MagLIF fuel or x-ray backlighting for various other experiments.

Fig. 11. Schematic of the ZPW and ZBL co-injection area.

Fig. 12. Comparison between short- and long-pulse backlighting scenarios for MagLIF.

Fig. 13. Comparison of laser illumination without a phase plate and defocused (left) and a similar sized illumination with a $750~\unicode[STIX]{x03BC}\text{m}$ phase plate at best focus. The images are scaled logarithmically to enhance lower intensity features of the spot without phase plate. The high intensity areas in the unconditioned beam (without phase plate) can cause filamentation and LPI amplification.

Fig. 14. Comparison of a 4 kJ shot with a phase plate (top) and a 2 kJ shot with unconditioned beam at roughly $700~\unicode[STIX]{x03BC}\text{m}$ diameter (bottom). Despite the higher energy, there is a dramatic reduction of SBS for the case with a large diameter focal spot.

Fig. 15. Existing (a) and modified (b) ZBL architecture in order to accommodate the need for an AO system.

Fig. 16. Phasics software screenshot of calibration measurement.

Fig. 17. Phasics software screenshot of $1\unicode[STIX]{x1D714}$ cw alignment beam passing through a cold amplifier beam train. The inset on the upper left shows the $1\unicode[STIX]{x1D714}$ FF measured in the diagnostic box on the mezzanine.

Fig. 18. Phasics software screenshot of $1\unicode[STIX]{x1D714}$ cw alignment beam passing through a static aberration corrected cold amplifier beam train. The inset on the upper left shows the $1\unicode[STIX]{x1D714}$ FF measured in the diagnostic box on the mezzanine. Note that the filter and gain settings on the FF camera are the some for both insets.

Fig. 19. Phasics software screenshot of an uncorrected full system shot.

Fig. 20. Phasics software screenshot of a pre-corrected full system shot.