FUSION HYPOTHESES
        David A. Dietzler, 2007
D+T (deuterium+tritium) fusion is "easiest."  D+D fusion is more "difficult."  D+he3 fusion is even "tougher" to get.  Fusion depends on temperature, plasma density and plasma confinement time.  The temperature (in keV) times the plasma density (particles per cubic meter) times the confinement time (seconds) equals the Lawson parameter.  A DT plasma must have a Lawson parameter of 10E21 to reach breakeven and 4*10E21 for ignition.  For a D-He3 plasma L= 10E22 for ignition (1). The reason D+he3 fusion requires higher temps, plasma density and confinement time is because of the "protonic" or positive electrical charge repulsion between the one proton of D and the two protons of he3.  Will the greater electrical charge of he3 make it bond to the magnetic flux lines enough to overcome some of this effect by achieving a higher plasma density and longer confinement time?  Will the charged particles of D+he3 ( an 14.1 MeV proton and 4.3 MeV alpha particle) fusion impart enough energy to the plasma to heat it up without introducing energy from outside the plasma in the form of ohmic heating, microwaves, deutron beams or even lasers? 

Can we build tokamaks of a superior design to the ITER (international thermonuclear experimental reactor, it will generate merely 500 MW thermal, not much of a commerical reactor) with more powerful magnets based on more modern superconductors with higher current carrying capacity to generate a magnetic confinement field that will allow the plasma temps, D+he3 require without the plasma expanding and losing density?  And confine it long enough for "ignition?" 

Are the confinement characteristics of he3 really superior to D and T due to he3's higher charge to mass ratio?  D consists of one proton and one neutron so its charge to mass ration is 0.5.  T consists of 2 nuetrons and one proton so its charge to mass ratio is 0.33.  Helium 3 consists of two protons and one neutron so its charge to mass ratio is 0.67.  How much difference does this make?   Finally, will the plasma self heating effects of D+he3 make a significiant difference?  Can we tap energy with MHD from ions that fly out of the plasma and make the fusion reactor more efficient by recovering some energy?  Will higher temp. superconductors reduce the cooling energy load enough to make the reactor more efficient?   

The advantage of he3 fusion is nuclear power without nuclear waste.  Even a D+T reactor will generate nuclear waste.  The 14.1 MeV neutrons must be captured in a hot corrosive lithium jacket to tap their energy and provide heat for steam turbines.  How long will such a reactor last with that hot corrosive lithium jacket and constant bombardment by high energy neutrons?  Will the neutrons penetrate the lithium jacket and transmute the superconductors into non-superconducting substances and ruin the machine for good?

If D+he3 fusion can be achieved soon, the Moon's he3 will be of immense value, and our expensive exploration of the Moon will have yielded fruit, as explorations in the past have done. 
The Z-pinch coil compresses the magnetic flux lines so that ions cannot get thru, sort of like the coils in a Penning trap do, and the ions collide and reverse and collide some more, fusing in the process and releasing energy.

Plasma that escapes from flux lines will go thru MHD system and to heat exchanger to generate hot working fluid for turbines.  This will recover lost energy that can be used to heat more plasma to fusion temperature.  Unburnt D and he3 is recovered on substrates of some kind or even compressed and cooled and separated and injected into torus again.

Fusion reactors require energy to work.  For commercial success a fusion reactor must generate at least 3x as much energy as is pumped into it.  At first, energy for fusion reactors will come from hydroelectric dams.  Later, electricity could come from solar power satellites, thus there is a synergy between fusion and SPS power.  If 10 TW is supplied by 1000 SPS to run fusion reactors 30 TW could result.  Combined with a superconducting power grid and GEO power relay satellites we could provide electricity for the entire planet in the second half of the 21st century from outer space.  Can it be done? It would be revolutionary. 
Fusion and fusion plasmas have been studied for 50+ years.  Building a D+he3 reactor should be a problem in straighforward engineering without much in the way of new physics.  Larger, more efficient magnetic containment coils to confine the D+he3 long enough at higher density and AT HIGHER TEMPs which cause the ions to become so energetic that they break free from the magnetic flux lines leading to plasma instability and chaos (like fire) and loss of plasma density (thereby reducing the number of collisions at high enough energy for fusion)  in such a short amount of time that there is no time for decent energy production, are necessary.  High temp superconductors now exist and should reduce the cooling load.  Should he3 really have better containment properties than tritium and should the a-particles and protons reallly heat the plasma to ignition, presuming we have these better magnetic containment systems, then D+He3 fusion is just a matter of investing the money into D+He3 research reactors by government and industry.  We can mass produce rockets, perhaps Saturn Vs or Ares Vs, and lower the cost of launching, and mine the Moon for helium 3.  This much I am certain of. 
Linear fusion reactors are more suited to MHD power generation than tokamaks and might be cheaper to build in large numbers someday.  However, linear fusion reactors have not been as successful as tokamaks largely because of leakage from the ends of the magnetic containment chamber.  Perhaps not enough research spending has been devoted to fusion reactors of various kinds.  With superior magnets and superconductors, perhaps there will be a revival of linear fusion reactor research.