ANS NETS 2022: Nuclear and Emerging Technologies for Space An Extremely High Isp Spacecraft Propulsion System Authors: - L. P. Forsley (GEC, NASA), Deputy PI, NASA LCF Project - T. L. Benyo, Ph.D. (NASA), PI, NASA LCF Project - P. A. Mosier-Boss, Ph.D. (GEC), Senior Scientist - L. A. Dudzinski (NASA), Chief Technologist, Planetary Science Division Affiliations: Global Energy Corporation (GEC), NASA Lattice Confinement Fusion (LCF)¹ Measured Nuclear Reactions: NASA JSC Linear Energy Transfer Analysis of Solid State Nuclear Track Detectors (CR-39) from two experiments²,³ at SRI. e.g., ⁷Li(d,n)2α 3-body nuclear reaction Graph: Protons and Alpha Particles - Shows particle count vs Particle energy in MeV (ranging from ~2 to 15 MeV), detailing reactions: d(d,p)t, Pd(d,n)p, ⁷Li(d,n)2α, Pd(p,γ)Ag, d(³He,p)α. Proposed Application: Lattice Confinement Fusion reaction charged products for high Isp propulsion: - D(³He,p)α > 14.8 MeV proton, 3.4 MeV α - Pd(d,n)p > 6 MeV proton - ⁷Li(p,α)α > two 8.5 MeV α LCF: Triggered fusion in electron-screened, high-density deuterated metal lattices. Footnotes: ¹ Baramsai, et al., "NASA’s New Shortcut to Fusion Power: Lattice Confinement Fusion Eliminates Massive Magnets and Powerful Lasers", IEEE Spectrum (March, 2022). ² P.A. Mosier-Boss, et al., "Detection of high energy particles using CR-39 detectors part 1: Results of microscopic examination, scanning, and LET analysis", Int. J. of Hydrogen Energy, 42, 1 (2017) pp 416-428. ³ US Patent #8,419,919, "System and Method for Generating Particles", (2013). Specific Impulse: It’s all about the exhaust velocity! • Specific Impulse is a measure of rocket engine efficiency expressed in seconds - Isp = ve / go where ve is the propellant exhaust velocity in m/s, go = 9.8 m/s² Propulsion System Comparison Table: - Chemical: Exhaust Velocity (ve) < 4.4 x 10³ m/s | Specific Impulse (Isp) < 4.5 x 10² s | Thrust: High - Nuclear Thermal: Exhaust Velocity (ve) ≈ 9.0 x 10³ m/s | Specific Impulse (Isp) ≈ 9.0 x 10² s | Thrust: High - Solar Electric: Exhaust Velocity (ve) ≈ 2.9 x 10⁴ m/s | Specific Impulse (Isp) ≈ 3.0 x 10³ s | Thrust: Low - VASIMR®¹,²: Exhaust Velocity (ve) ≈ 1.2 x 10⁵ m/s | Specific Impulse (Isp) ≈ 1.2 x 10⁴ s | Thrust: Variable - Nuclear Fusion³: Exhaust Velocity (ve) ≈ 3.5 x 10⁵ m/s | Specific Impulse (Isp) ≈ 3.5 x 10⁴ s | Thrust: High - LCF: Exhaust Velocity (ve) > 1.5 x 10⁷ m/s | Specific Impulse (Isp) > 1.5 x 10⁶ s | Thrust: Variable High Isp usually means low thrust, but with nearly continuous acceleration! Footnotes: ¹ http://web.mit.edu/mars/Conference_Archives/MarsWeek04_April/Speaker_Documents/VASIMREngine-TimGlover.pdf (2004). ² VASIMR®: Variable Specific Magnetoplasma Rocket ³ C.H. Williams, L. A. Dudzinski, S. K. Borowski and A. J. Juhasz, "Realizing '2001: A Space Odyssey': Piloted Spherical Torus Nuclear Fusion Propulsion", NASA/TM-2005-213559. An Extremely High Isp Propulsion System • Alpha particles > 6 MeV have exhaust velocities approaching 5% speed of light! - c = 3x10⁸ m/sec (speed of light in vacuum) - ve > 1.5 x 10⁷ m/sec (propellant exhaust velocity) - Isp > 10⁶ sec • ≈ 10,000 times chemical rocket Isp • ≈ 1,000 times Solar Electric Propulsion (SEP) ion thruster Isp • ≈ 100 times VASIMR® Isp • Charged particles can be directed by magnetic and electric fields • Magnetohydrodynamics (MHD) can be used to power the spacecraft with a loss of Isp • LCF is an inherently low thrust system, but offers continuous acceleration like SEP - Thrust can be traded off against Isp by heating and expelling heavier mass