A new approach to natural controlled fusion1 February 2002
In this proposed nuclear fusion process, only those light nucleus fusion reactions are used which produce very high energy neutrons and alpha particles. By: H S Brar
In this nuclear fusion process, it is intended that only those light nucleus fusion reactions are used which produce very high energy neutrons and alpha particles. The energy of these fast particles is used partly in order to split the deutrons, and partly to produce fast deutrons, tritons and lithons by collisions within the moderator and fuel (Lithium Deutride with a minute quantity of Lithium Tritide).
The energy that is spent by 14Mev neutrons on breaking the deutrons is more than compensated when additional generated neutrons get absorbed within the lithium 6 nucleii. Slow neutrons that are left after they have transferred their energy are further used to produce fast tritons and protons in the fuel. Tritons produced in this way are used just after their creation when they have very high velocity.
These fast moving deutrons, tritons and protons are produced in random directions just atomic distances away from other fixed deuterium, tritium and lithium nuclei, throughout the fuel in the reactor core. The fuel may be in solid or liquid form, depending upon the reactor. The arrangements and materials employed in this type of fusion reactor are shown in the sketch on page 27.
Following these concepts, a fusion reactor of practical dimensions can be made. In these types of reactors, the fusion reaction rate depends upon the population of fast tritons and fast deutrons, which in turn depend upon the fast neutron population. Therefore fusion reactor power can be controlled by conventional methods, in the same way of those methods that are employed to control present day fission reactors.
While they are slowing down in a moderator, the fast neutrons transfer a considerable portion of their energy on each collision to light nuclei such as protons, deutrons and tritons. A fast neutron can generate many fast moving light nuclei. Fast neutrons can be produced inexpensively by the most likely DT fusion reactions in a controlled fusion reactor. Fast neutrons are far superior for fusion reactions when compared to mu-mesons and lasers.
In a deutron, the neutron and proton are loosely bound. Fast neutrons and fast protons containing energy that is greater than 3.5Mev is able to split the deutron into its constituent parts. Very high energy neutrons or protons then hits one of the particles of a deutron very hard. Thereafter, splitting a deutron, two particles remain fast and one slow. A 14Mev fast neutron either splits three deutrons or two deutrons. When three deutrons are split, four fast particles and three slow particles are generated from only one high energy particle. These four fast particles further generate around 20 fast deutrons in fuel having lithium deuteride, which can undergo fusion reactions.
Because of their much larger size and their single charge, deutrons possess a very high nuclear fusion reaction cross-section when in potential collison with other suitable nuclei like tritons and lithons. At aprroximately 100kev energy, the fusion cross-section of fast tritons with deutrons is appreciably greater than 1 barn.
Positively charged nuclei transfer a considerable part of their energy to electrons while they are in motion. These electron encounters can be minimised by using only light nuclei in fuel for nuclear fusion reactions. This applies only to lithium and to hydrogen isotopes.
The energy of the fast moving alpha particles and protons is transferred quickly and efficiently to the tritons and deutrons in order to utilise a part of their energy to produce some fusion reactions.
As positively charged nuclei lose their energy over a very short range, for the most efficient nuclear fusion reactions, the reacting nuclei containing sufficient energy have to be produced locally in all directions throughout the fuel. Slow neutrons can produce high energy particles by (n, a) and (n, p) reactions with light nuclei, such as:
Li6 + n slow 950b a + T + 4.66Mev
Thus from a slow neutron, a triton of 2.66Mev is produced which has a very high fusion reaction probability with deutrons if they are suitably positioned. Thus the tritons have to be used just after their production. As a result of this, the neutrons can be used to control the fusion reaction rate and also for the linking of the different zones in a fusion reactor. The production of many photoneutrons will further help to make control of the reactor easy.
The local production of a sufficient density of fast charged particles in a solid or liquid fuel also solves the unique and formidable confinement problem for such very high temperature (about 109°C particles). This problem is presently being faced in plasma fusion reactors. Natural electric fields, which were previously considered to be unsuitable, possessed by the nuclei and electrons of the fuel are employed to confine the fast moving positive charged nuclei.
The arrangement and materials that are employed for the construction of a fusion reactor are shown in the sketch below. Neutron source starting device and control devices are not shown in the sketch for the sake of clarity. Li7T in the required quantity (which is yet to be derived by experiment) must be added to the fuel, in order to gain the previously described advantages, and to reduce the size of the fusion reactor to manageable dimensions. Once in operation, the fusion reactor will produce more tritium than it consumes . helium, along with other gases from relief valves, has to be collected in a separate vessel in order to limit the pressure inside the fuel elements.
The cycle of a fusion reactor based upon the above principles
Step 1: Production of very fast particles by fusion reactions.
• D + Tfast a + n + 17.6Mev
• Li7 + Dfast Be8 + n + 16Mev
• Li7 + pfast (2 a + 17.4Mev) or
(2 a + g + 17.4 Mev)
• Li6 + Tfast 2 a + n + 16Mev
• D + He3fast a = p + 18.3 Mev
• Li7 + Li6fast C12 + n + 23Mev
• Li6 + Dfast - 2 a + 22Mev
Step 2: Splitting deutrons by very fast particles.
• nf(E>3.5Mev) + Dtarget nf1 + (n+p) one fast and one slow
• pf (E>3.5Mev) + Dtarget pf1 + (n+p) one fast and one slow
Step 3: Further production of fast charged particles by fast particles from steps 1 and 2.
The fast particles in step 1 and step 2 transfer part of their energy on each collision to deutrons, tritons and lithons, and each fast particle produces many fast charged particles of sufficient energy which can undergo nuclear fusion reactions easily. In this process, all the fast neutrons become slow neutrons.
Step 4: production of fast tritons, fast neutrons, fast protons and fast He3 particles.
• Li6 + nslow a + T + 4.66Mev
• D + Dfast T + p + 4Mev
• D + Dfast He3 + n + 3.3Mev
• Li6 + Dslow Li7 + p + 5Mev
• He3 + nslow T + p + 0.74Mev
• Be7 + nslow Li7 + p + 1.65Mev
Fast charged particles produced in steps 3 and 4 go for further nuclear fusion reactions and will theoretically produce appreciably more than one very fast neutron per very fast neutron of the previous generation. Following these concepts, a self-sustaining and energy releasing process can be set up. Essentially, this is a neutron multiplying system, hence the nuclear fusion reaction rate can be controlled by conventional methods, such as by neutron absorption, by controlling neutron leakage, or by varying neutron supply from outside sources (such as from linear accelerators) to a sub-critical assembly.