High Energy Propulsion

Brice CassentiUniversity of Connecticut

High Energy Propulsion

• Fusion• Annihilation• Photon

Fusion Energy

• Binding energy• Reactions• Propulsion

Binding Energy

Some Fusion Reactions(1)

2 1D +

3 1T →

4 2He ( 3.5 MeV ) + n0 ( 14.1 MeV )

(2i) 2 1D +

2 1D →

3 1T ( 1.01 MeV ) + p+ ( 3.02 MeV )

50%

(2ii)

→ 3 2He ( 0.82 MeV ) + n0 ( 2.45 MeV )

50%

(3) 2 1D +

3 2He →

4 2He ( 3.6 MeV ) + p+ ( 14.7 MeV )

(4) 3 1T +

3 1T →

4 2He

+ 2 n0

+ 11.3 MeV

(5) 3 2He +

3 2He →

4 2He

+ 2 p+

+ 12.9 MeV

(6i) 3 2He +

3 1T →

4 2He

+ p+ + n0

+ 12.1 MeV

51%

(6ii)

→ 4 2He ( 4.8 MeV ) +

2 1D ( 9.5 MeV )

43%

(6iii)

→ 4 2He ( 0.5 MeV ) + n0 ( 1.9 MeV ) + p+ ( 11.9 MeV ) 6%

(7i) 2 1D +

6 3Li →

2 4 2He

+ 22.4 MeV

(7ii)

→ 3 2He +

4 2He

+ n0

+ 2.56 MeV

(7iii)

→ 7 3Li + p+

+ 5.0 MeV

(7iv)

→ 7 4Be + n0

+ 3.4 MeV

(8) p+ + 6 3Li →

4 2He ( 1.7 MeV ) +

3 2He ( 2.3 MeV )

(9) 3 2He +

6 3Li →

2 4 2He

+ p+

+ 16.9 MeV

(10) p+ + 11 5B →

3 4 2He

+ 8.7 MeV

http://en.wikipedia.org/wiki/Nuclear_fusion

Nuclear Reactions

• DT Fusion Reaction

• Uranium Fission

• Lithium Fission

10

42

31

21 nHeHH

10

23892

10 2

21

1nXXUn N

kN

k

31

42

63

10 HHeLin

Fusion Reactions

• The DT reaction

• And Lithium fission reaction

• Are equivalent to

10

42

31

21 nHeHH

31

42

63

10 HHeLin

42

42

63

2 HeHeLiH1

Reaction Cross-Section

Reaction Kinetics

• Rate -

• Parameter -

• Velocity depends on temperature

–

– k is Boltzmann’s constant

nv

v

kTmv2

3

2

1 2

Rate vs. Temperature

http://www.google.com “nuclear fusion reactor pictures”

Thermonuclear Weapon

Magnetic Confinement Fusion PowerTokamak

http://upload.wikimedia.org/wikipedia/commons/4/4b/Tokamak_fields_lg.png

Magnetic Confinement Fusion PowerMirror

http://www.google.com “magnetic mirror nuclear fusion reactor pictures”

Inertial Confinement Fusion Power

The stages of inertial confinement fusion:

1. Laser beams or laser-produced X-rays rapidly heat the surface of the fusion target, forming a surrounding plasma envelope.

2. Fuel is compressed by the rocket-like blowoff of the hot surface material. 3. During the final part of the capsule implosion, the fuel core reaches 20 times the density

of lead and ignites at 100,000,000 ˚C. 4. Thermonuclear burn spreads rapidly through the compressed fuel, yielding many times

the input energy.

The blue arrows represent radiation; orange is blowoff; purple is inwardly transported thermal energy.

http://en.wikipedia.org/wiki/File:Inertial_confinement_fusion.svg

Fusion Rockets

• Magnetic Mirror– End fields unequal: preferential exhaust

• Tokamak– Power to expel high speed plasma

• Inertial Confinement– Magnetic nozzles align pellet products

Orion

Daedalus StudyBritish Interplanetary Society

From Nicolson “The Road to the Stars”

Daedalus

http://www.grc.nasa.gov/WWW/PAO/images/warp/warp44.gif

Medusa

http://en.wikipedia.org/wiki/File:MedusaNuclearPropulsionOperatingSequenceDrawing.png

Medusa

Specific Impulse:100,000-500,000

http://en.wikipedia.org/wiki/File:MedusaNuclearPropulsionOperatingSequenceDrawing.png

Matter-Antimatter Annihilation

ee

Positron-Electron Annihilation

nnmpp 0

nnmpn )1(0

Antiproton-Uranium Nucleus Annihilation

+

p

p

n

knXUp 223892

Courtesy of G. Smith

Pellet Ignition

Tritium Fuel Considerations

• Tritium is naturally radioactive– Beta decay– Half-life ~12 years

• Tritium requires cryogenic storage• Lithium-6 is not radioactive• Lithium-6 does not require cryogenic storage

Pellet Construction

Hybrid Fusion-Fission Nuclear Pulse Propulsion

• Use of Li6 – Reduces tritium handling problems– Decreases specific impulse

• System can be developed in a two step process– Use fusion to boost the specific impulse of a pulse

fission rocket– Evolve to a full hybrid system

Typical PelletGeometry

• Core radius 0.05 mm• Fuel Radius 1.00 cm• Tungsten Shell Thickness 0.10 mm• Antiproton Beam Radius 0.10 m• Uranium Hemisphere Radius 0.30 mm

Typical Pellet Performance

• Antiproton Pulse 2x1013 for 30 ns• Maximum Field 24 MG• Pellet Mass 3.5 g• Specific Impulse

– 600,000 s for 100% fusion– 200,000 s for 10% fusion– 3,000 s for contained fusion

Exotic Propulsion Alternatives

Sanger Electron-PositronAnnihilation Rocket

By G. Matloff

Proton-Antiproton Reaction

nnmpp 0

Proton-Antiproton Reaction

nnmpp 0

Proton-Antiproton Reaction

nnmpp 0

Proton-Antiproton Reaction

nnmpp 0

ee

ee

Proton-Antiproton Reaction

nnmpp 0

ee

ee

+

Proton-Antiproton Reaction

nnmpp 0

ee

ee

+

Pion Rocket

By R. ForwardIsp: 10,000,000 sec

References• Kammash, T., (editor), Fusion Energy in Space Propulsion, Volume 167 Progress in

Astronautice and Aeronautics, American Institute of Aeronautics and Astronautics, Washington, DC,, 1995.

• Kammash, T, Fusion Reactor Physics, Ann Arbor Physics, Inc. Ann Arbor, MI, 1976.• Manheimer, W.M., An Introduction to Trapped-Particle Instability in Tokamaks,

Energy Research and Development Administration, Washington, DC, 1972.• Miley, G.K., Fusion Energy Conversion, American Nuclear Society and U.S. Energy

research and Development Administration, Chicago, 1976.• Miyamoto, K., Plasma Physics for Nuclear Fusion, The MIT Press, Cambridge, MA,

1987.• Vedenov, A.A., Theory of Turbulent Plasma, National Aeronautics and Space

Administration, National Science Foundation, and Isreal Program for Scientific Translations, Jerusalem, 1966.