1. Nuclear Fission and Fusion UMA LAD PHY 3305: MODERN PHYSICS DECEMBER 2, 2014

2. Outline Fission and fusion will be defined. Examples of fission and fusion will be discussed. Modern day applications of these reactions will be discussed. 12/02/2014LAD MODERN PHYSICS2

3. Nuclear Reaction Occurs when a nucleus collides with another particle Example: uranium- 235 decays into barium and krypton 12/02/2014LAD MODERN PHYSICS3 Total Energy released: Q= (m i – m f )c 2

4. Nuclear Fission Nucleus breaks down into many parts Releases kinetic energy Many isotopes decay through induced fission Number of protons and neutrons affects the amount of energy released 12/02/2014LAD MODERN PHYSICS4 Fig. 1. Uranium Fission. “Mousetrap Reactor.” SMU Physics and Astronomy Demonstrations. 2014. Web. 25 Nov. 2014.

5. Chain Reactions Each fission reaction will cause other fission reactions to occur. Critical assembly: ensures that a reaction can sustain itself 12/02/2014LAD MODERN PHYSICS5 The energy released during a chain reaction: E j = E 0 k j

6. Fission Reactor Uranium-235 is used as the fuel Control rods absorb neutrons Neutrons produced from each generation become slower 12/02/2014LAD MODERN PHYSICS6

7. 12/02/2014LAD MODERN PHYSICS7 Pressure Water Reactor Fig. 2. A Light-Water Nuclear Fission Reactor for the Production of Electric Power. Digital image. ”Applied Nuclear Chemistry.” UC Davis Chemwiki. UC Davis, n.d. Web. 20 Nov. 2014.

8. Nuclear Fusion Nuclei combine to form heaver nuclei Mass decreases Kinetic energy increases 12/02/2014LAD MODERN PHYSICS8

9. Lawson Criterion For fusion to occur: High temperatures are necessary Reaction must be held: For a certain amount of time A certain density of ions 12/02/2014LAD MODERN PHYSICS9

10. 12/02/2014LAD MODERN PHYSICS10 Proton-Proton Cycle End result: helium Energy source of the Sun Fig. 3. Fission in the Sun. “Proton- Proton Chain Reaction.” Wikipedia. Wikimedia Foundation Inc., 2006. Web. 25 Nov. 2014.

11. Fusion in Relation to Stars Carbon Cycle Uses carbon as a catalyst Results in helium Occurs when a star has a high temperature Stellar Collapse- Star collapses into a white dwarf Energy production from fusion no longer matches the gravitational attraction 12/02/2014LAD MODERN PHYSICS11

12. Fusion Reactors Difficult to use as a power source Requires extreme conditions Ways to confine nuclei Magnetic confinement Inertial confinement 12/02/2014LAD MODERN PHYSICS12

13. Conclusion Fission - nucleus breaking down into many parts. Fusion - nuclei combining to form heaver nuclei. Chain reaction - one reaction triggers many other reactions. Fission reactors are used to produce energy. Proton-proton cycle is composed of multiple fusion reactions. 12/02/2014LAD MODERN PHYSICS13

14. Sources Harris, Randy. Modern Physics. 2nd ed. San Francisco: Pearson, 2008. 503-513. Print. Herrmann, Mark. “Plasma Physics: A promising advance in nuclear fusion.” Nature 506 (2014): 302-303. Web. 17 Nov. 2014. Nave, Rod. "Nuclear Fusion." HyperPhysics. Web. 11 Nov. 2014. <http://hyperphysics.phy-astr. gsu.edu/hbase/nucene/fission.html#c1>. Reed, Cameron B. “Neutrons as Party Animals: An Analogy for Understanding Heavy-Element Fissility.” The Physics Teacher 50 (2012): 544-545. Web. 17 Nov. 2014. 12/02/2014LAD MODERN PHYSICS14