Chapter 5 Thermonuclear Fusion 1Introduction 2. Thermonuclear Reactions and energy Production Basic reactions and Q values Cross sections 3. Fusion in a hot medium 4. Progress Towards Fusion Power Magnetic confinement Inertial confinement fusion 5. Stellar Burning
Chapter 5. Thermonuclear Fusion 1.Introduction 2.Thermonuclear Reactions and Energy Production 3.Fusion in a Hot Medium 4.Progress Towards Fusion Power 5.Stellar Burning
Nuclear fusion The fusion process Neutron protor Two nuclei combine into one nucleus plus a nucleon is Collision called nuclear fusion a nuclear reaction The picture here illustrates the fusion of D+犴T→4He+n that releases a lot of energy Fusion Fusion
Fusion 2 Nuclear Fusion Two nuclei combine into one nucleus plus a nucleon is called nuclear fusion, a nuclear reaction. The picture here illustrates the fusion of 2D + 3T → 4He + n that releases a lot of energy. The Fusion Process Collision Fusion Neutron proton
ncident Barrier Transmitted beam region i beam E x Distance Penetration through a rectangular energy barrier(height B )of a particle beam, of kinetic energy e(< B), incident from the left. The form of the wave functioni, 4 is sketched In the upper part of the figure. Inside the barrier, 4 is an exponentially decaying function of X The coulomb barrier between two + hydrogen nuclei is about 200 keV
Penetration through a rectangular energy barrier (height B) of a particle beam, of kinetic energy E (< B), incident from the left. The form of the wave functioni, Ψ is sketched In the upper part of the figure. Inside the barrier, Ψ is an exponentially decaying function of x. The Coulomb barrier between two hydrogen nuclei is about 200 keV
Nuclear Fusion Energy for D-T Fusion Estimate the fusion energy for d+t,4He+n Estimate the fusion energy Q The mass excess Mev) are given below every species d + t 4He 13.136+14950=2.425+8.070+Q Q=17.6 MeV/fusion This amount is 3.5 Me amu compared to 0.8 MeV/amu for fission Estimating Q is an important skill. Mass and mass excess can be used the latter is usually given to unstable nuclides
4 Nuclear Fusion Energy for D-T Fusion Estimate the fusion energy for D + T → 4He + n Estimate the fusion energy Q The mass excess (MeV) are given below every species. D + T → 4He + n + Q 13.136 + 14.950 = 2.425 + 8.070 + Q Q = 17.6 MeV/fusion This amount is 3.5 MeV/amu compared to 0.8 MeV/amu for fission. Estimating Q is an important skill. Mass and mass excess can be used, the latter is usually given to unstable nuclides
Nuclear Fusion Energy for Fusion Reactions Common fusion reactions and their Q values D+D→>4He++23.85MeV H+H→>D+βt+V+1.44MeV D+T→4He+n+176Me∨ D+3He→4He+p+184MeV D+D→3He+n+33MeV D+D→3T+p+4.0MeV ATOM LARGER ENERGY> See Interactive Plasma Physics Education ATOM Experiencehttp://ippEx.pppl.gov/ Fusion ATOM
Fusion 5 Nuclear Fusion Energy for Fusion Reactions Common fusion reactions and their Q values D + D → 4He + n + 23.85 MeV H + H → D + + + n + 1.44 MeV D + T → 4He + n + 17.6 MeV D + 3He → 4He + p + 18.4 MeV D + D → 3He + n + 3.3 MeV D + D → 3T + p + 4.0 MeV See Interactive Plasma Physics Education Experience : http:// ippex.pppl.gov/
Effective Cross Section(mb) of Fusion Reactions Nuclear Fusion 10000 Cross sections D+T→4e+ 1000 Cross sections data from reactions studied using particles from cyclotron 100 D+D→+p Li(p, n)'Be T(p e D+D→e+n H(t, n )3He D(d, n )H He→>4e+p D(t, n)4He T( d, n ) 4He 60 kev
Nuclear Fusion Cross Sections Cross sections data from reactions studied using particles from cyclotron 7Li (p, n) 7Be 3T (p, n) 3He 1H (t, n) 3He 2D (d, n) 3He 2D (t, n) 4He 3T (d, n) 4He Effective Cross Section (mb) of Fusion Reactions 0.1 1. 10 100 1000 10000 10 20 30 40 50 60 60 D + T → 4He + n D + D → 3T + p D + D → 3He + n D + 3He → 4He + p keV
Chapter 5 Thermonuclear Fusion 1Introduction 2. Thermonuclear Reactions and energy Production Basic reactions and Q values Cross sections 3. Fusion in a hot medium 4. Progress Towards Fusion power Magnetic confinement Inertial confinement fusion 5. Stellar burning
Chapter 5. Thermonuclear Fusion 1.Introduction 2.Thermonuclear Reactions and Energy Production 3.Fusion in a Hot Medium 4.Progress Towards Fusion Power 5.Stellar Burning
FUSION INA HOT MEDIUM Maxwell-Boltzmann Distribution p(u)du is the probability that the speed lies Fraction p(o)o exp(-mu/2kT)between v andv+dv The kinetic energy corresponding to the most probable speed is kT 0.003 0.002 4 amu 50 K Kinetic energies of particles in plasma follow the maxwell 0.001 4 amu 500 K Boltzmann distribution 1000 2000 3000 Speed(m/s) At room temperature, kT is about 0.025 ev 10K(kT a 10 kev)
Maxwell-Boltzmann Distribution 1000 2000 3000 0.001 0.002 0.003 4 amu 50 K 4 amu 500 K Speed (m/s) Fraction Kinetic energies of particles in plasma follow the MaxwellBoltzmann distribution FUSION IN A HOT MEDIUM The kinetic energy corresponding to the most probable speed is kT At room temperature, kT is about 0.025 eV is the probability that the speed lies between v and v + dv
Nuclear fusion and plasma D and t mixtures have to be Normal Atoms heated to 10 million degrees. at these temperatures, the mixture is a plasma A plasma is a macroscopically neutral collection of charged particles lons(bare nuclei at high temperature have high kinetic energy and they approach each other within 1 fm, a distance strong force being effective to cause fusion
Nuclear Fusion and Plasma D and T mixtures have to be heated to 10 million degrees. At these temperatures, the mixture is a plasma. A plasma is a macroscopically neutral collection of charged particles. Ions (bare nuclei) at high temperature have high kinetic energy and they approach each other within 1 fm, a distance strong force being effective to cause fusion
Reaction rate Consider a mixture of two gases consisting respectively of n and n2 particles per unit volume The probability for a particle in the first gas to react with one in the second, per unit distance travelled, is n20 The distance travelled per unit time is the speed v of the particle The reaction probability per unit time is nou total reaction rate per unit volume is R= nn20U Assume: n particles have the same speed and that the n2 particles of the second gas are stationary Reality: Maxwell-Boltzmann distribution (uo)=/p(o)o(o)udo R=nn2(bo
Reaction rate Consider a mixture of two gases consisting, respectively, of nl and n2 particles per unit volume. total reaction rate per unit volume is Assume: nl particles have the same speed and that the n2 particles of the second gas are stationary Reality: Maxwell- Boltzmann distribution The probability for a particle in the first gas to react with one in the second, per unit distance travelled, is The distance travelled per unit time is the speed v of the particle The reaction probability per unit time is