Affordable, manageable, practical, and scalable high-yield and high-gain inertial fusion Nathan Meezan on behalf of the Pacific Fusion team ARPA-E Fusion Programs, Denver CO 7/9/2025 Pacific Fusion What is Pacific Fusion doing with its Series A? - Building the Demonstration System. PF will be first to net facility gain and first to high yield (>100 MJ) fusion. - Driver technology, diagnostics, target design and fabrication, facility operations, etc. - Designing the most affordable pulsed fusion power plant fleet to begin scaled deployment starting next decade. - Repetitive firing, operations & maintenance, construction, regulatory, separations, balance of plant, etc. - Developing additional applications and technologies that support both. - Advanced manufacturing and fusion supply chain building, transportable radiation effects systems, pulsed power technologies. PF is building a fusion Demonstration System to achieve net facility gain Key Specifications & Capabilities: - 80 MJ stored energy - >10 MJ coupled to target - Flexible pulse shaping capabilities - Designed for > 100 MJ DTn (Qf > 1) - Remote handling for hazardous operations System Components: - A: Pulser module - B: Transmission line - C: Water Dome - D: Chamber - E: Target PF’s Demonstration System is based on the Impedance-matched Marx Generator (IMG)¹ - Brick is a low inductance switch/cap configuration - Each stage outputs a power pulse at the desired pulse length - Pulse travels down the module, triggering the next stage - No pulse sharpening needed - Higher efficiency than traditional Marx generators (e.g. Z) - Highly modular architecture enables operational flexibility Components shown: Brick (switch, capacitors), Stage (anodes, cathode), Module, Pulser array. ¹ W. Stygar et al., Phys. Rev. Acc. Beams 20, 040402 (2017) PF’s DS system model combines transmission line circuits and 2D and 3D fully electromagnetic insulators and full vacuum plasmas - Simulations have 1000+ circuit element circuit - 2D/3D EM vacuum stack - 3D plasma power flow at R < 1 m - DS delivers >60 MA in a 4.5 nH inner MITL - ~80% of IMG power delivered to vacuum section - Build waypoint: Half of DS towers delivers >45 MA (initial capability mid 2028) PF is developing a full range of diagnostic instruments to support DS experiments from commissioning to high yield (100+ MJ) Diagnostics Suite: - X-ray Imaging and radiography: GALAXI, DIPPER, VIRGO - X-ray power and energy: CRAB - X-ray Spectroscopy: SPICE - Neutron Spectra: nTOF (x3), MARS - Neutron Imaging: ENDOR (x2) - Burn History: RIDE, NGC, CEKOV - Optical: VISAR, PDV, FARAD (See AMPS paper for details) Target Cassette & Chamber: - Chamber (R ~ 4 m) - 12° Port, Equatorial Port, Lid Puller, Laser Tracker - Remote insertion of precision target package - Offline setup, metrology, vacuum prep, and cryogenics for target PF’s approach is Pulser IFE (MagLIF), which has demonstrated the second highest laboratory Pτ - Pulser IFE is Inertial Fusion - Pulser IFE has the advantages and benefits of ICF: - Large flexible driver paired with small (~cm) flexible targets - Sound theoretical basis - A method to quantitatively measure proximity to ignition - ICF codes, institutions, and community - Pulser IFE takes advantage of the high efficiency of the IMG - Pulser IFE has favorable scaling paths to high yield Reference chart: S. E. Wurzel and S. C. Hsu, Phys. Plasmas 29, 062103 (2022), updated. PF’s approach is Pulser IFE (MagLIF), which has demonstrated the second highest laboratory Pτ Physics & Operation: - Current density (J) and magnetic field (B) create J x B compressive force - Sequence: Magnetization -> Laser Heating -> Compression - Implosion driven by magnetic forces - Does not require maintaining an equilibrium - At stagnation, magnetic forces are dwarfed by material pressure - Target length scale ~ cm, time scale ~ 100 ns Reference: M. R. Gomez, and S. A. Slutz et al., Phys. Rev. Lett. 113, 155003 (2014) PF is benchmarking target design capabilities against data and published laboratory rad-hydro MHD simulations - FLASH is a 3D, multispecies, Eulerian AMR code with multigroup radiation diffusion and MHD - FLASH is widely available, DOE/NNSA-funded, and used by >4000 researchers worldwide - PF is co-developing FLASH with the Flash Center at the University of Rochester - PF has validated FLASH against Z data and simulations: - Hydro instabilities (MRT, RM) - MagLIF experiments - Similarity scaling magLIF to 60 MA - Validation shows excellent agreement with data and state-of-the-art ICF design codes. - FLASH Validation Manuscript - Includes MagLIF Similarity Scaling from Ruiz et al 2023 comparing FLASH and HYDRA with/without alpha heating up to 60 MA. PF is using FLASH to design for ignition and high gain on the DS - 2D MagLIF target in FLASH simulation - 2D MagLIF FLASH results for Be design and Al design: - Alpha-on yields reaching ~21 MJ - Alpha-off yields ~1-2 MJ - Yield amplification from alphas ~ 7-20 - Energy delivered to liner ~ 5 - 11 MJ across time (155-171 ns) PF’s IMG pulser + direct-drive IFE (MagLIF) is efficient and energy rich Comparison of energy flow: NIF Laser-hohlraum drive vs. DS Pulser magnetic drive: - NIF: Capacitors (~330 MJ) -> Laser to hohlraum -> Absorbed by capsule -> Work on fuel -> Hot spot internal energy (with efficiencies ηD, ηhohl, ηimp ηstag). - DS Pulser magnetic drive: Capacitors (80 MJ) -> Vacuum stack -> Delivered to target (>8 MJ) -> Work on liner (Emech) -> Fuel internal energy (~1 MJ) -> Hot spot internal energy. - Key finding: At ~60 MA, PF’s DS can deliver > 8 MJ to the target and ~ 1 MJ to the DT fuel. PF’s IMG pulser + direct-drive IFE (MagLIF) is efficient and energy rich - Efficient IMG pulser technology - Efficient direct-drive scheme - PF’s pulser IFE approach is efficient, low cost, and high tempo Facility gain can be achieved for pulser ICF with NIF-ignition-like fuel gain and burn-up fraction Consider a 6 mm-tall MagLIF-like design with 300 micron DT ice shell driven at Imax ≈ 60 MA: | Metric | NIF Ignition* | Be DS target | Al DS target | |---|---|---|---| | Energy stored in capacitors | 330 MJ | 80 MJ | 80 MJ | | Energy delivered to target | 2.2 MJ | 8.3 MJ | 8.4 MJ | | DT fuel mass | 0.22 mg | ≈ 10.6 mg | ≈ 10.2 mg | | Nuclear energy yield | 5.2 MJ | 109 MJ | 380 MJ | | Qtarget = YTN / Edriver | ≈ 2.4 | ≈ 13 | ≈ 45 | | Qfuel = YTN / Eint,DT | ≈ 260 | ≈ 100 | ≈ 350 | | DT burn-up fraction ϕ | 7 % | 3 % | 10 % | | Facility gain Qf | 0.016 | 1.36 | 4.75 | * A. L. Kritcher et al., Phys. Rev. E 109, 025204 (2024) estimated from 8.2 kJ @ 2.0 MJ laser energy. NIF numbers should be revised upward based on shot generating 8.6 MJ from 2.08 MJ laser energy.