From: g_d_pusch_remove_underscores@xnet.com   
      
   khallow@hotmail.com (Karl Hallowell) writes:   
      
   > g_d_pusch_remove_underscores@xnet.com (Gordon D. Pusch) wrote in message   
   news:...   
   >   
   >    
   >   
   >> Only in press releases, since no one else has been able to replicate   
   >> the alleged effect, and there are strong theoretical reasons to believe   
   >> that the alleged effect cannot possibly exist; this strongly suggesting   
   that,   
   >> very much like "cold fusion," it was an example of "pathological science,"   
   >> i.e., the claimants either screwed up, or are deluding themselves.   
   >>   
   >> Also, even if it _did_ work as claimed (which I =VERY= strongly doubt!)   
   >> note that the alleged energy would be released as _gamma rays_, which are   
   >> arguably the second most USELESS and IMPRACTICAL form of energy conceivable!   
   >> (About the only thing that could possibly be worse would be neutrinos!)   
   >   
   > Actually, neutrons are further down on the impractical list than gamma   
   > rays. Part of the reason breakeven fusion is so hard to achieve - the   
   > fusion reaction keeps losing energy through neutron emission.   
      
   You are confused on a number of points.   
      
   First, neutrons are _MUCH_ easier to absorb than gamma rays, since they   
   feel the strong force, and many nuclei have quite large neutron absorption   
   cross sections.   
      
   Second, the primary energy-loss mechanisms from a fusion plasma are   
   bremsstrahlung radiation and synchrotron radiation, which are both fancy   
   terms for "X-rays." These X-rays are emitted simply because the plasma is   
   very, very hot, and rapidly cool off the plasma. By contrast, the plasma   
   does not emit significant amounts of neutrons unless it is hot enough that   
   a significant rate of fusion reactions are occuring.   
      
   Third, the reasons why "Breakeven" has been hard to achieve are that:   
   A.) Magnetically confined plasmas are very unstable and difficult to   
      confine (someone once compared it to being "like trying to hold jello   
      in a cage made of rubber bands);   
   B.) It has been difficult to pump heat energy into the plasma faster than   
      bremsstrahlung and synchrotron radiation carry it away.   
      
   The combination of plasma instabilities and bremsstrahlung losses has meant   
   that so we have not been able to keep a plasma dense enough and hot enough   
   for long enough that it will "ignite."   
      
   Fourth, fusion reactions do not "lose energy" through neutron emission;   
   rather, when a deuterium and a tritium nucleus fuse, their _reaction products_   
   are a 3.5 MeV alpha particle and a 14.1 MeV neutron. In an "ignited" plasma,   
   the alphas will provide more than enough heat energy to keep the reaction   
   going,   
   while the neutrons, being uncharged, will zip right through the magnetic field   
   to be absorbed in the reactor's shielding blanket, where they will produce heat   
   for conversion into useful energy, while simultaneously breeding new tritium   
   fuel.   
      
      
   -- Gordon D. Pusch   
      
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