Compact Fusion Reactor, CFR

Summary

This presentation introduces Lockheed Martin’s Compact Fusion Reactor (CFR) concept, focusing on high-beta magnetic confinement using encapsulated linear ring cusps in a magnetic bottle field. It outlines the nominal and conservative reactor design points, plasma stability and inflation physics, scaling challenges, results from the T4 experimental campaign, and the phased development path toward a prototype power plant.

Compact Fusion Reactor, CFR

The Lockheed Martin CFR Concept

• LM Philosophy, need and mission – 1.3 B without electricity, 18% of world, EIA International Energy Outlook 2013 (IEO2013) – +56% energy consumption and +93% electricity generation from 2010 to 2040, EIA International Energy Outlook 2013 (IEO2013) – @ $3/ W,$ 210B/yr in new electrical power plant sales alone • Compact, elegant…rapid development, short cycles. High beta • Favorable reactor geometry – Similar method: J. P. Freidberg, F. J. Mangiarotti, and J. Minervini, Physics of Plasmas 22, 070901 (2015). • Nominal Reactor Design Point – 200 MW Thermal, T = 14 keV, n = 1.8·10^20 m^-3, V = 30.8 m^3. – 1 m blanket, 80%/20% FLIBE/Steel, 3.2 g/cc, 4 MW/m^2 neutron wall load – Core: 5.2 m diameter by 15.2 m long, 230 mt – B_β=1 = 1.4 T, p = 7.8 atm, B_mirror = 4.2 T, 9 MA mirror current • Conservative Reactor Design Point – 200 MW Thermal, T = 14 keV, n = 6.3·10^19 m^-3, V = 247 m^3. – 2 meter blanket, 5 g/cc, 1 MW/m^2 neutron wall load – Core: 10.5 m diameter by 30.5 m long, 1900 mt – B_β=1 = 0.84 T, p = 2.8 atm, B_mirror = 5.0 T, 20 MA mirror current Diagram annotations: natural divertor, diamagnetic plasma sheath, superconducting magnets, steady-state stable DT fusion plasma, neutral beam injectors, blanket absorbs neutrons to breed fuel and transfer heat to turbines. © 2015 Lockheed Martin Corporation. All Rights Reserved.

Vacuum Fields and Stability

Magnetosphere/null Line, Stability Boundary, Limiter
Stability Plot for Outer Mirror Flux Tubes: Stable, dV/dr < 0
Stability Plot for Inner, Recirculation Flux Tubes: Stable Everywhere, dV/dr < 0
Beta = 1 design line, center line, cylindrical HTS superconducting coils (10 MA, 1 MA, 7 MA, 1 MA, 4.3 MA) © 2015 Lockheed Martin Corporation. All Rights Reserved.

High Beta Inflation

• Vacuum field is a set of linear ring cusps encapsulated by a bottle field – Beta = 1 surfaces are in-board of cusps – Line-averaged global interchange stability is achieved, only locally-bad curvature in ring cusps • Interchange pushes plasma into magnetic wells, observed in initial low power experiments – Heating creates plasma at discrete locations in volume, propagates along field lines – Pressure gradients should kick off turbulence that will organize a diamagnetic plasma – As plasma pressure increases, Beta = 1 sheath boundary should ‘inflate’ and fill up chamber volume. – Need sufficient heating to fully ionize background gas and to raise temperature to levels that reduce CX collisions and mirror losses. Equations & Loss Channels:

Magnetized sheath losses: P_S ≈ (L_M * r_p * n_s^2) / B_p ≈ (r_p^2 * n^2) / T^(1/2) P_i,s = 3/2 * e(T_i + eφ_p) * L_i [W], P_e,s = 3/2 * e(T_e - eφ_p) * L_e [W], L_s = (n_s * V_s) / (2 * τ_ii), τ_ii = 2·10^13 * (μ^(1/2) * T_i^(3/2)) / (n_s * λ_ii) [s]
Unmagnetized ring cusp losses to coil supports: P_R ≈ (r_p * n * T^2) / B_p ≈ r_p * n^2 * T^(1/2) P_i,R = 3/2 * e(T_i + eφ_p) * Γ_i,R * A_R * %i · S = (24 * sqrt(2) / sqrt(pi)) * e(T_i + eφ_p) * sqrt(eT_i / m_i) * (n_R / n) * (e * n_i / n_s) * (N_s * a_R / R_s) * S * δ_R [W] P_e,R = 3/2 * e(T_e - eφ_p) * Γ_e,R * A_R * %i · S = (24 * sqrt(2) / sqrt(pi)) * e(T_e - eφ_p) * sqrt(eT_e / m_e) * (n_R / n) * (e * n_e / n_s) * (N_s * a_R / R_s) * S * δ_R [W] Annotations: neutral beam heat, ring cusp losses to stalks, axial cusp losses, sheath losses exit axially, diffusion loss to coil, plasma sits in magnetic wells, trapped magnetized sheath, center line. © 2015 Lockheed Martin Corporation. All Rights Reserved.

Fully Inflated Confinement Scaling and Challenges

• Steady-state – Need a consistent equilibrium solution, complex kinetic plasma • Main losses – Magnetized sheath, ion losses from positive plasma – Unmagnetized ring cusp losses to supports – Charge exchange losses – Line radiation – Bremmstrahlung radiation – Unmagnetized cusp losses on axis – Diffusion across magnetic fields to walls • Ionization and heating – ECRH – LaB6 – Plasma gun – Electron or ion beam – Neutral beam initialization – Alpha product self-heating • Biggest challenges and questions – Cusp behavior – drives scaling and shielding requirements – Shielding implementation – 90% reduction needed for hybrid gyro – Microinstabilities, ExB and stability during inflation transient – Plasma facing surfaces, neutron damage and blanket design – Tritium lifecycle and containment Scaling formula: Q = P_f / P_L = (1.3 * e * Y * <σv>) / [ 1.6·10^-33 * (n_s / n)^2 * (1 / (r_p * B_p)) (Sheath) + 2·10^-44 * (n_R / n) * (S / (r_p^2 * B_p^3)) * T^3 (Support) + 5.2·%I * Q_k + 8.9·10^-38 * Z_eff * T^(1/2) (Radiation terms) ] Annotations: alpha heating from DT fusion plasma, neutral beam heat, trapped magnetized sheath, ring cusp losses to stalks, axial cusp losses, sheath losses exit axially, diffusion loss to coil, center line. © 2015 Lockheed Martin Corporation. All Rights Reserved.

Development Path

• Progression of fast experiments with parallel sub-system work – T4 – Investigate CFR plasma configuration – T5 – Demonstrate high Beta – T6 – Demonstrate high power (1 MW), high temperature (1 keV) – T7 – Demonstrate reactor conditions with Deuterium plasma – T8 – Demonstrate ignited DT plasma for short durations (<10 sec) • Parallel sub-system development – Plasma simulation – Neutral beam heating development – Superconducting magnetic field coils – Internal coil support shielding – Blanket design and power plant design • Engineering and product development, towards a T-X Reactor – Energy conversion cycle – Materials, tritium cycle, servicing – Regulation, environmental impact, ITAR, military applications © 2015 Lockheed Martin Corporation. All Rights Reserved.

Current T4 Experiments

• T4 goal: Investigate CFR plasma configuration – V_plasma = 0.33 m^2, V_chamber = 2 m^3. – n_background = 3·10^18 m^-3 D2 gas – 0-15 kW 2.4 GHz ECRH, axial injection – Peak mirror magnetic field 0.6 T, shot duration ~1 sec. • Results, 482 shots to date – Observe plasma organization in magnetic wells – ECRH cut-off limits ability to reach full ionization, <10% – At higher powers, observe outer regions filling with plasma – Peaked density profiles in core, flat T_e with increased power – Typical n = 10^16 m^-3 - 10^17 m^-3, T_e = 10-25 eV, τ_E = 4-100 μsec Diagnostics listed: Microwave interferometer, Diamagnetic loops, Bolometer, Soft x-ray - UV spectrometer, Hard x-ray, Visible spectroscopy, High-speed imaging, Langmuir probe, B-dot probe. Plots: (far left) FastCam visible imager, (left) ion density vs. probe location, (center) electron temperature vs. power at different probe locations. Error bars represent the standard deviation of values calculated from I-V sweeps taken multiple times during the run. (right) line-averaged density from interferometer averaged over shot. Error bars are the result of signal noise and magnetic field effects. Blue line is a linear fit to the data. © 2015 Lockheed Martin Corporation. All Rights Reserved.

Future Work and Collaboration Opportunities

T5 plan • Fully ionized plasma, LaB6 source and washer gun • Improved diagnostics – Langmuir probes, b-dot probes, ES analyzer, spectroscopy, Thomson scattering, flux loops • Neutral beam heating development, hot high beta • Alternate heating: axial electron and ion beam heating • Simulations – Plasma equilibrium – HPC PIC plasma studies, high Beta cusp behavior, inflation transients, magnetic shielding – Blanket design, lightweight and low-cost designs • Magnetic support shielding and superconducting coil design • Currently hiring in Palmdale, CA. 14 open positions – Plasma experimentalist, plasma theory, pulsed power, beam, laser, electronics, mechanical © 2015 Lockheed Martin Corporation. All Rights Reserved.

Closing Slide

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