Achievement of Target Gain Larger than Unity in an Inertial Fusion Experiment

On December 5, 2022, an indirect drive fusion implosion on the National Ignition Facility (NIF) achieved a target gain G_{target} of 1.5. This is the first laboratory demonstration of exceeding "scientific breakeven" (or G_{target}>1) where 2.05 MJ of 351 nm laser light produced 3.1 MJ of total fusion yield, a result which significantly exceeds the Lawson criterion for fusion ignition as reported in a previous NIF implosion [H. Abu-Shawareb et al. (Indirect Drive ICF Collaboration), Phys. Rev. Lett. 129, 075001 (2022)PRLTAO0031-900710.1103/PhysRevLett.129.075001]. This achievement is the culmination of more than five decades of research and gives proof that laboratory fusion, based on fundamental physics principles, is possible. This Letter reports on the target, laser, design, and experimental advancements that led to this result.

Lawson Criterion for Ignition Exceeded in an Inertial Fusion Experiment

For more than half a century, researchers around the world have been engaged in attempts to achieve fusion ignition as a proof of principle of various fusion concepts. Following the Lawson criterion, an ignited plasma is one where the fusion heating power is high enough to overcome all the physical processes that cool the fusion plasma, creating a positive thermodynamic feedback loop with rapidly increasing temperature. In inertially confined fusion, ignition is a state where the fusion plasma can begin "burn propagation" into surrounding cold fuel, enabling the possibility of high energy gain. While "scientific breakeven" (i.e., unity target gain) has not yet been achieved (here target gain is 0.72, 1.37 MJ of fusion for 1.92 MJ of laser energy), this Letter reports the first controlled fusion experiment, using laser indirect drive, on the National Ignition Facility to produce capsule gain (here 5.8) and reach ignition by nine different formulations of the Lawson criterion.

Demonstration of ignition radiation temperatures in indirect-drive inertial confinement fusion hohlraums

We demonstrate the hohlraum radiation temperature and symmetry required for ignition-scale inertial confinement fusion capsule implosions. Cryogenic gas-filled hohlraums with 2.2 mm-diameter capsules are heated with unprecedented laser energies of 1.2 MJ delivered by 192 ultraviolet laser beams on the National Ignition Facility. Laser backscatter measurements show that these hohlraums absorb 87% to 91% of the incident laser power resulting in peak radiation temperatures of T(RAD)=300 eV and a symmetric implosion to a 100 μm diameter hot core.

A phase I trial of the monoclonal antibody FG-3019 to connective tissue growth factor (CTGF) in locally advanced or metastatic pancreatic cancer

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Background: CTGF is highly expressed in pancreatic tumors and is thought to mediate local desmoplasia. FG-3019 is a fully human monoclonal antibody against CTGF. Studies using FG-3019 in murine xenograft models have shown reduced tumor growth and metastasis.

Methods: This open-label, dose escalation study assessed the safety and pharmacokinetics of FG-3019 (3, 10, 15, and 25 mg/kg q14D). FG-3019 was initiated on D1 to assess single-agent toxicity. Standard gemcitabine and erlotinib were added on D15. Chemotherapy-naive patients with locally advanced or metastatic adenocarcinoma were eligible. Seventeen subjects (median age 66 yrs) were enrolled: n=4, 3, and 10 at 3, 10, and 15 mg/kg respectively. Enrollment is ongoing in the 25 mg/kg cohort. Seven subjects were female; four were stage 3, and 13 were stage 4.

Results: No safety signals were detected with single-agent FG-3019. After beginning chemotherapy, four subjects experienced seven SAEs, which were deemed unrelated to FG-3019 including three deaths: sepsis, suicide, and disease progression. Nine subjects experienced grade 3 AEs, all of which were expected in patients with pancreatic cancer. There were no grade 4 hematologic abnormalities. AEs related to gemcitabine (hematologic, abnormal LFTs) and erlotinib (rash) occurred at a rate and severity consistent with the prescribing information (preliminary data). Steady-state Cmax (median 428, range 236-455 μg/mL), and T1/2 (median 6.6, range 6.3-6.7 days) at the 10 mg/kg dose level were comparable to PK data from subjects in non-oncological trials who received FG-3019 at the same dose level. One subject had a partial response by RECIST criteria for 9.7+ months. Another subject had a minor response for 7.7 months. Three of five subjects with PET scans at baseline and D15 experienced stable to reduced PET activity before starting chemotherapy. The median TTP across all cohorts was 3.7 months (95% CI 1.9-6.2), and the median OS was 9.4 months (95% CI 1.9-10.6).

Conclusions: FG-3019 is well tolerated and dose escalation continues. Reduced PET activity after treatment with single-agent FG-3019 may indicate a biological effect of the agent.

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Demonstration of high-energy 2 omega (526.5 nm) operation on the National Ignition Facility Laser System

A single beamline of the National Ignition Facility (NIF) has been operated at a wavelength of 526.5 nm (2 omega) by frequency converting the fundamental 1053 nm (1 omega) wavelength with an 18.2 mm thick type-I potassium dihydrogen phosphate (KDP) second-harmonic generator (SHG) crystal. Second-harmonic energies of up to 17.9 kJ were measured at the final optics focal plane with a conversion efficiency of 82%. For a similarly configured 192-beam NIF, this scales to a total 2 omega energy of 3.4 MJ full NIF equivalent (FNE).

National Ignition Facility laser performance status

The National Ignition Facility (NIF) is the world's largest laser system. It contains a 192 beam neodymium glass laser that is designed to deliver 1.8 MJ at 500 TW at 351 nm in order to achieve energy gain (ignition) in a deuterium-tritium nuclear fusion target. To meet this goal, laser design criteria include the ability to generate pulses of up to 1.8 MJ total energy, with peak power of 500 TW and temporal pulse shapes spanning 2 orders of magnitude at the third harmonic (351 nm or 3omega) of the laser wavelength. The focal-spot fluence distribution of these pulses is carefully controlled, through a combination of special optics in the 1omega (1053 nm) portion of the laser (continuous phase plates), smoothing by spectral dispersion, and the overlapping of multiple beams with orthogonal polarization (polarization smoothing). We report performance qualification tests of the first eight beams of the NIF laser. Measurements are reported at both 1omega and 3omega, both with and without focal-spot conditioning. When scaled to full 192 beam operation, these results demonstrate, to the best of our knowledge for the first time, that the NIF will meet its laser performance design criteria, and that the NIF can simultaneously meet the temporal pulse shaping, focal-spot conditioning, and peak power requirements for two candidate indirect drive ignition designs.