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Agenda

Thermal Analysis of a Radiation Shield for Antimatter Rocketry Concepts Jon Webb Embry Riddle Aeronautical University. Agenda. Why Hyperion Rocket Principles Why antimatter Velocity Profile and Fundamentals Thermal Considerations. Why fly so fast in space?. Space flight takes to long!.

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Agenda

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  1. Thermal Analysis of a Radiation Shield for Antimatter Rocketry ConceptsJon WebbEmbry Riddle Aeronautical University HYPERION ERAU

  2. Agenda • Why Hyperion • Rocket Principles • Why antimatter • Velocity Profile and Fundamentals • Thermal Considerations HYPERION ERAU

  3. Why fly so fast in space? Space flight takes to long! HYPERION ERAU

  4. Microgravity Environment Skeletal and Muscular atrophy can make it impossible to return to the surface of Earth! HYPERION ERAU

  5. Cosmic Radiation Radiation in space is lethal!! HYPERION ERAU

  6. Rocket Principles • Specific Impulse is the fuel efficiency of a rocket engine • As fuel energy density increases so does Specific Impulse and delta V • The equation for Specific Impulse is: HYPERION ERAU

  7. Rocket Principles • Thrust is a force • Thrust is the time rate change of propellant momentum • Momentum is the mass of fuel ejected multiplied by the exhaust velocity HYPERION ERAU

  8. Chemical Rocketry • LO/LH2 HYPERION ERAU

  9. Fuel Energy Density HYPERION ERAU

  10. What is antimatter (positrons) • Produces photons isotropically • Produces photons back to back • 0.511 MeV per photon HYPERION ERAU

  11. How do we propel a S/C HYPERION ERAU

  12. Shield Design (Rad. Lengths) HYPERION ERAU

  13. Shield Design • Made of Tungsten • Melting point of 3600 K • Density of 19.3 gm/cm3 • Radiation length is 0.35 cm • 5 radiation lengths thick • Roughly 1.75 cm thick HYPERION ERAU

  14. Shield Design (Dimension) HYPERION ERAU

  15. Shield Design (Mass) HYPERION ERAU

  16. Momentum Attenuation electron • Compton Scattering • Brehmstralling • Photo-electric Effect • photons/electrons ejected at random angles • Might reduce momentum/cosine average • Monte-Carlo analysis is being developed to research effects Atom HYPERION ERAU

  17. Thermal Problem • Energy is lost as heat in the tungsten shield • We must find a way to dissipate the heat in order to augment the thrust • We must find a way to regain the energy lost from the heat to augment efficiency (Isp) HYPERION ERAU

  18. Shield Thermal Loading HYPERION ERAU

  19. Radiative Cooling • For highest Isp we must find the steady state condition where blackbody radiation equals input energy. • This will severely limit the thrust Eradiated E thermal , P thrust HYPERION ERAU

  20. Radiative Cooling • View Factors must be examined • The extreme limits of the pi/2 to –pi/2 shield may re-radiate energy into the other side of the shield. HYPERION ERAU

  21. Radiative Cooling • We may want to consider making the shield flat and very large, or decrease the angular limits of the shield. • Annihilate e+ inside shield HYPERION ERAU

  22. Radiative Cooling R R AP D All Values in Radians HYPERION ERAU

  23. Radiative Cooling HYPERION ERAU

  24. Radiative Cooling HYPERION ERAU

  25. Radiative Cooling HYPERION ERAU

  26. Radiative Cooling 1. 7. 2. 3. 8. 4. 5. 6. HYPERION ERAU

  27. Radiative Cooling HYPERION ERAU

  28. Radiative Thrust HYPERION ERAU

  29. Convective Cooling • Use liquid Hydrogen or Ammonia to absorb excess heat • Allow fluid to expand across the shield to produce thrust with a decreased Isp HYPERION ERAU

  30. Convective Cooling LH2 Properties • Cp = 10,000 J/ (kg.K) • h = 210 W/(m2.K) • TLH2 = 16 K • Tshld = 3300 K HYPERION ERAU

  31. Convective Power Transfer 1. 2. HYPERION ERAU

  32. LH2 Mass Flow Rate 3. 4. 5. HYPERION ERAU

  33. LH2 Mass Flow Rate HYPERION ERAU

  34. Convective Thrust from LH2 6. 7. 9. 10. HYPERION ERAU

  35. Convective Thrust from LH2 HYPERION ERAU

  36. Shield Thrust to Weight Ratio HYPERION ERAU

  37. Convective Specific Impulse 11. 12. 13. 14. HYPERION ERAU

  38. Specific Impulse vs. Shield Temp. HYPERION ERAU

  39. Thrust Augmentation • Shield Mass: 170 Mt • 10 Shields • Shield Area: 10,000m2 • Thrust: 1.70 MN • Isp: 826 seconds 10 sub-shields 5 rad. lengths HYPERION ERAU

  40. Convective Case Study 1 • MS/C = 40 Mt • F = 1.70 MN • A = 10,000 m2 • P = 6,896 MW • Msh = 170 Mt • Md = 210 Mt • Mdote+ = 7.662 x 10-8 kg/s • MdotH2 = 210 kg/s HYPERION ERAU

  41. Convective Case Study 1 HYPERION ERAU

  42. Convective Case Study 1 HYPERION ERAU

  43. Convective Case Study 2 • MS/C = 40 Mt • F = 261.9 kN • A = 1130.4 m2 • P = 780 MW • Msh = 19.2 Mt • Md = 66.113 Mt • Mdote+ = 4.33 x 10-9 kg/s • MdotH2 = 23.7 kg/s HYPERION ERAU

  44. Convective Case Study 2 HYPERION ERAU

  45. Convective Case Study 2 HYPERION ERAU

  46. Convective Case Study HYPERION ERAU

  47. Further Convective Work • Combine case studies into 3-D graphs (dV vs. IMLEO/H2/e+ mass vs. shield mass/radius/area) • Research energy/heat deposition as a function of thickness plus H2 gaps • Increase SA without increasing mass HYPERION ERAU

  48. Electrical Power Production • Another option is to use a working fluid that can be expanded through a turbine to produce electricity • This would allow for low thrust missions and provide the spacecraft with electricity for its subcomponents HYPERION ERAU

  49. Tri-Modal Operation • Lastly the engine could be cooled with LH2 when large thrust is needed and operate in a radiative mode to slowly accelerate S/C in interplanetary space. • When the engine is in a radiative mode, electricity can be produced HYPERION ERAU

  50. Concluding Remarks • Antimatter offers extraordinary propulsion capabilities • Unfortunately thermal challenges are quite daunting • Production and storage are a whole different challenge HYPERION ERAU

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