A poster discussing the use of mechanical adiabatic compression in nuclear fusion

Kraft, David W.

UB ScholarWorks

 A Novel Approach to Fusion Power Generation  David W. Kraft Professor of Mathematics & Physics, College of Arts and Sciences University of Bridgeport, Bridgeport, CT Summary and conclusions    Energy is released when light nuclei fuse to form heavier nuclei. This is the energy which powers stars such as the Sun.  The amount of energy released is related to the difference in the masses of the initial and final nuclei according to E = mc2.  Nuclear forces are of short range.  Hence reactions occur only when nuclei are in close proximity and to achieve this they must have energy sufficient to overcome their repulsive electrostatic  forces.  This requires such high temperatures as 15,000,000 K as in the Sun.    What is Nuclear Fusion?      Challenges and objectives •Achieve temperatures such as that in the Sun’s interior; •Confine reacting species long enough for fusion reactions to occur; •Achieve energy break-even: output energy compensates input energy. Two Major Approaches to Fusion  Magnetic confinement. A low density plasma of H+  ions is confined by magnetic fields.  Inertial confinement.  A pellet of solid H is bombarded by high-intensity lasers.      Fusion reaction rates proportional to n2.     n = particle density.     Magnetic confinement methods:    n  1015 cm3     requires T  108 K  Proposed Method  Exploit n2 factor and reduced degrees of freedom     Perform under adiabatic conditions  appreciable fusion rates at lower T Mechanical adiabatic compression D2 gas Piston Insulated chamber walls Dense gas of D2 undergoes adiabatic compression Rapid process - - explosively driven Well-insulated chamber – retain energy internally  Starting conditions.       One mole D2 at atmospheric pressure and room temperature.  Apply compression.  T increases. D2 molecules  D2 atoms  D2 atoms ionize   deuteron-electron plasma  Fusion of deuterons.  Assumptions.   Make simplifying assumptions.  Reversible adiabatic compression  Apply equilibrium thermodynamics  Ideal gas behavior: PV = NRT (Initially, then non-ideal gas)  Adiabatic compression of ideal gas  PV = constant;   TV-1 = constant;      = specific heat ratio.  P = P0,   T = T0-1 ,   Compression factor:  = V0 / V.     Work to compress ideal gas  Exploited n2  factor and reduced degrees of freedom. Adiabatic conditions  energy retained internally. Found some favorable cases. To be more realistic:       Not all input energy serves to compress gas.       Consider particle losses via leakage. Compensated by ignoring:       D-T reactions; Pinch Effect.       Enhancements: Deuterated walls;  Screening effects of electrons.     Degrees of freedom  related to number of degrees of freedom f of the gas:  = (f + 2) / f   Rewrite eq’ns in terms of f:   T = T0 2 / f      W = ½P0V0f 2 / f.  For monoatomic gas:  f = 3 Deprive particles of freedom of motion  larger T increase for given energy input.   Accomplish with  (1) External magnetic field(s)  (2) Electric discharge in direction of piston motion.  Also  Pinch Effect     0 0110 0 0 00 0 1 .1 1V VV VPV PVW PdV PV V dV               Applications           Single shot:  Neutron source to initiate fission.        Multiple compressions in dual chambers.                                   Dual pistons with coil to extract work Primary reactions: D + D  T + p + 4.03 MeV;      D + D  3He + n + 3.27 MeV <v>  10-14 T-2/3 exp(-19T-1/3) cm3 / s  for T < 50 keV  Secondary reactions D +T   + n + 17.6 MeV;   D + 3He   + p + 18.3 MeV   Consider only D+D:  Av’g Q = 3.65 MeV   Energy release Reaction rate:  r = ½ n2 <v>      = reaction cross section;  v = relative velocity of interacting nuclei  Simplification  Fusion occurs only at end of compression.  Energy release in time t:  E = r Q V t Q = average energy release/reaction;   V = final volume Calculate E / W and burnup fraction  r t (n0)-1  for :  Q = 3.65 MeV,   t = 0.001 s,   f = 3, 2, 1,            = 100, 200. f  T ( K )  E / W B u r n 3 100 6  10 3  10 – 8 5  10 – 9 2 3 200 1  10 4  10 – 7 1  10 – 7 8 2 100 3  10 4  10 – 6 8  10 – 7 4 2 200 6  10 4  10 – 5 6  10 – 6 2 1 100 3  10 6  0.0 0 1  10 - 8 1 200 1  10 7 1 4  0.0 0 1  Note:  f =1,  = 100, 200.    Improve with longer t. Data for Ideal Gas # 72 :  __  __  __ 

A Novel Approach to Fusion Power Generation

https://scholarworks.bridgeport.edu/xmlui/bitstream/handle/123456789/318/6.Kraft.pdf?sequence=2&isAllowed=y

A Novel Approach to Fusion Power Generation

Abstract

Similar works

Full text

Available Versions

UB ScholarWorks