Winterberg compares his Super Marx generator pure deuterium micro-detonation ignition concept to the Lawrence Livermore National Ignition Facility (NIF) Laser DT fusion-fission hybrid concept (LiFE)
In a Super Marx generator a large number of ordinary Marx generators charge up a much larger second stage ultra-high voltage Marx generator, from which for the ignition of a pure deuterium micro-explosion an intense GeV ion beam can be extracted. A typical example of the LiFE concept is a fusion gain of 30, and a fission gain of 10, making up for a total gain of 300, with about 10 times more energy released into fission as compared to fusion. This means a substantial release of fission products, as in fusion-less pure fission reactors. In the Super Marx approach for the ignition of a pure deuterium micro-detonation a gain of the same magnitude can in theory be reached. If feasible, the Super Marx generator deuterium ignition approach would make lasers obsolete as a means for the ignition of thermonuclear micro-explosions
Up until now nuclear fusion by inertial confinement has only been achieved by using a fission explosive as a means (driver) for ignition. This is true not only for large thermonuclear explosive devices, like the 1952 pure deuterium Mike Test (carried out in the South Pacific with the Teller-Ulam configuration), but also for small deuterium-tritium (DT pellet) micro-explosions, (experimentally verified with a fission explosive at the Nevada Test Site by the Centurion-Halite experiment). From this experience we know that the ignition is easy with sufficiently large driver energies, but which are difficult to duplicate with lasers or electric pulse power.
Winterberg believes substantially larger driver energies can be reached by a “Super Marx generator”. It can be viewed as a two-stage Marx generator, where a bank of ordinary Marx generators assumes the role of a first stage. If the goal is the much more difficult ignition of a pure deuterium micro-explosion, the Super Marx generator must in addition to deliver a much larger amount of energy (compared to the energy of the most powerful lasers), also generate a magnetic field in the thermonuclear target that is strong enough to entrap the charged DD fusion products within the target. Only then is the condition for propagating thermonuclear burn fulfilled. For this to happen, a 100 MJ-1GeV-10^7 Ampere proton beam is needed.
An ignition an energy of 100 MJ and a yield of 23 GJ, the fusion gain would be G = 230, about the same as for the LiFE concept. However, since even in pure deuterium burn neutrons are released through the secondary combustion of the tritium D-D fusion reaction products, a much higher overall gain is possible with an additional fission burn, as in the LiFE concept
The energy of up to a gigajoule, delivered in ~ 10-7 seconds at a power of 10^16 Watt, opens up other interesting possibilities.
1. If instead of protons heavy ions are accelerated with such a machine at gigavolt potentials, these ions will upon impact be stripped off of all their electrons, in case of uranium all of its 92 electrons. Accordingly this would result in a 92 fold increase of the beam current to ~ 10^9 Ampere. With such an ultrahigh current, a very different fusion target
seems possible, where a solid deuterium rod is placed inside a hollow metallic cylinder. The inner part of the beam I1 will directly pass through the deuterium inside the cylinder, while the outer part of the beam I0 will be stopped in the cylindrical shell, there depositing its energy and imploding the shell onto the deuterium cylinder, at the same time compressing the azimuthal magnetic beam field inside the cylinder. If ignited at the position where the beam hits and ignites the cylinder, will lead to a deuterium detonation wave propagating down the cylinder.
2. At a beam current of ~ 10^9 Ampere, will lead to a large, inward directed magnetic pressure. At a beam radius of 0.1 cm, the magnetic field will be of the order of 2×10^9 Gauss, with a magnetic pressure of 10^17 dyn/cm2 ≈ 10^11 atmospheres. At these high pressures the critical mass of fissile material (U235, Pu 23a, and U233) can be reduced to ~ 10-2 g . This would make possible micro-fission explosion reactors not having the meltdown problem of conventional fission reactors.
3. In general, the attainable very high pressures would have many interesting applications. One example is the release of fusion energy from exotic nuclear reactions, like the pB11 neutron-free fusion reaction, conceivably possible under very high pressures.
The fusion/fission LiFE concept proposed by the Livermore National Laboratory is an outgrowth of the DT laser ignition project pursued at the National Ignition Facility. Ignition is there expected in the near future. With its large fission component, it is difficult to see how the LiFE can compete with conventional fission reactors. Like them it still has the fission product nuclear waste problem. For this reason it hardly can without fission solve the national energy crisis, for what it has been billed by California Governor Schwarzenegger.
The proposed Super-Marx concept is by comparison a much more ambitious project, because it recognizes that the fundamental problem of inertial confinement fusion is the driver energy, not the target. And that only with order of magnitude larger driver energies can real success be expected. This in particular is true, if the goal is to burn deuterium. Unlike deuterium which is everywhere abundantly available, the burn of deuterium-tritium depends on the availability of lithium, a comparatively rare element. In conclusion, we display a table comparing the two different concepts.
Brian Wang is a Futurist Thought Leader and a popular Science blogger with 1 million readers per month. His blog Nextbigfuture.com is ranked #1 Science News Blog. It covers many disruptive technology and trends including Space, Robotics, Artificial Intelligence, Medicine, Anti-aging Biotechnology, and Nanotechnology.
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