Oppenheimer Phillips vs. stripping in fusion and neutron production
Posted: Sun Apr 25, 2021 12:42 am
The deuteron is a relatively loosely bound nuclei. Its charge center is not the center of mass of the nucleus and is constantly changing. Thus, it is electrostatically susceptible to charge exchange reactions, especially at lower energies with other deuterons. So long as the deuterons never hit head on and classically fuse to helium 4, (very rare), charge exchange fusions at low energies are possible due to the relatively long time period the deuterons are in close proximity to each other. (Glancing blows and even very close misses.) Here, the quantum uncertainties of lopsided charge centers have a higher probability of fusion exchanges due to lengthened times of interaction. This is the Oppenheimer-Phillips reaction. It is the one we use to do fusion. It only happens at lower energies. A look at the D-D fusion cross section shows that fusion increases up to the 1-2 MeV level and then nose dives.
"Stripping" is possible and is the cause of the above nose dive and reduced fusion after 2MeV. The deuterons at this energy will not fuse but are literally ripped apart into protons and neutrons at 4 MeV. Naturally, at a sufficiently higher energy you will get twice the neutrons and twice the protons from this stripping reaction than from genuine D-D fusion.
The lower energy "true" D-D fusion can begin at amazingly low energies, 5keV and above. However, the Oppenheimer-Phillips reaction cross section has a very sharp rise due to the battle between the electrostatic coupling in charge exchange reactions occurring with more effective shearing force at higher energies, (speeds), versus time to allow for quantum uncertainty to have the ideal lopsided charge presentations at the correct moment while passing or glancing deuterons might interact. A sort of electrostatic brisance, if you will, due to higher energies 20Kev-500keV.
We note the cross section really loses "steam", (reduced slope) above 200keV due to the high velocity of D-D encounters, coupled with the still rare probabilistic opportunities for the quantum lopsided charge centers to align for charge/particle exchange.
The upshot is that D-D fusion is not one so much of classic particle collision, but more of a true electrostatically induced fusion via charge exchange reactions still governed by quantum uncertainty of charge distributional alignment in these non-charge-centric small nuclei.
Admittedly, I must now confess that I had thought, and expounded in the past, that both of the two reactions being discussed in this FAQ were one and the same. Recent, more extensive reading and study have given my earlier exhortations related to stripping and the O-P reaction the lie. All here might have noticed a rather long period since much active fusion work has come from me. I have been doing a lot more intensive studying, reading and introspection related to D-D fusion. D-D fusion is what we do and deserves the best treatment in the FAQs possible. All of my musing about quantum tunneling is still valid, but for far more clear and easy to grasp reasons. Quantum uncertainty controls that chance of nuclear charge exchange probability.
I Have always felt and continue to feel that this very uncertainty limits the success of any fusion for net energy gain here on earth that is within any sort of cost effectiveness weighed against output power versus input power in a reactor that functions on a continuously operated schedule.
Musings.......
It seems that deuterons which might be confined at zero relative velocity within a certain fermi closeness might simply, due to this very same charge exchange reaction of fixed nuclear proximity might fuse as in a chain reaction!! This smacks at the loading of Deuterium-palladium in the old cold fusion, (CF), scenario. Unfortunately, molecular separations of deuterium atoms itching to fuse via the above OP charge exchange reactions in metal lattices are not compact enough. Remember the Lawson criteria. In a lattice, D atoms are in rather close proximity with the special willingness to simply do charge exchange fusion, confined in time forever. So many claims of excess energy, well measured on only very rare instances were recorded in the CF work of the past. It just proved not to be easily or even regularly repeatable. One must open one's mind on this one. In the NIF hohlraum, are the lasers raising the temperature to fusion energies or collapsing the D-T hohlraum like a Pu fission core to do fusion? I can't say for sure. Are we are too conditioned to thermal fusion? There is a hint at quantum, naturally induced, electrostatic charge-exchange fusion with D and T! Can we take off the "input, hot energy blinders" we are so conditioned to?? Worth thinking about.
Richard Hull
"Stripping" is possible and is the cause of the above nose dive and reduced fusion after 2MeV. The deuterons at this energy will not fuse but are literally ripped apart into protons and neutrons at 4 MeV. Naturally, at a sufficiently higher energy you will get twice the neutrons and twice the protons from this stripping reaction than from genuine D-D fusion.
The lower energy "true" D-D fusion can begin at amazingly low energies, 5keV and above. However, the Oppenheimer-Phillips reaction cross section has a very sharp rise due to the battle between the electrostatic coupling in charge exchange reactions occurring with more effective shearing force at higher energies, (speeds), versus time to allow for quantum uncertainty to have the ideal lopsided charge presentations at the correct moment while passing or glancing deuterons might interact. A sort of electrostatic brisance, if you will, due to higher energies 20Kev-500keV.
We note the cross section really loses "steam", (reduced slope) above 200keV due to the high velocity of D-D encounters, coupled with the still rare probabilistic opportunities for the quantum lopsided charge centers to align for charge/particle exchange.
The upshot is that D-D fusion is not one so much of classic particle collision, but more of a true electrostatically induced fusion via charge exchange reactions still governed by quantum uncertainty of charge distributional alignment in these non-charge-centric small nuclei.
Admittedly, I must now confess that I had thought, and expounded in the past, that both of the two reactions being discussed in this FAQ were one and the same. Recent, more extensive reading and study have given my earlier exhortations related to stripping and the O-P reaction the lie. All here might have noticed a rather long period since much active fusion work has come from me. I have been doing a lot more intensive studying, reading and introspection related to D-D fusion. D-D fusion is what we do and deserves the best treatment in the FAQs possible. All of my musing about quantum tunneling is still valid, but for far more clear and easy to grasp reasons. Quantum uncertainty controls that chance of nuclear charge exchange probability.
I Have always felt and continue to feel that this very uncertainty limits the success of any fusion for net energy gain here on earth that is within any sort of cost effectiveness weighed against output power versus input power in a reactor that functions on a continuously operated schedule.
Musings.......
It seems that deuterons which might be confined at zero relative velocity within a certain fermi closeness might simply, due to this very same charge exchange reaction of fixed nuclear proximity might fuse as in a chain reaction!! This smacks at the loading of Deuterium-palladium in the old cold fusion, (CF), scenario. Unfortunately, molecular separations of deuterium atoms itching to fuse via the above OP charge exchange reactions in metal lattices are not compact enough. Remember the Lawson criteria. In a lattice, D atoms are in rather close proximity with the special willingness to simply do charge exchange fusion, confined in time forever. So many claims of excess energy, well measured on only very rare instances were recorded in the CF work of the past. It just proved not to be easily or even regularly repeatable. One must open one's mind on this one. In the NIF hohlraum, are the lasers raising the temperature to fusion energies or collapsing the D-T hohlraum like a Pu fission core to do fusion? I can't say for sure. Are we are too conditioned to thermal fusion? There is a hint at quantum, naturally induced, electrostatic charge-exchange fusion with D and T! Can we take off the "input, hot energy blinders" we are so conditioned to?? Worth thinking about.
Richard Hull