LPPFusion is trying to develop aneutronic fusion with a dense plasma focus device. A dense plasma focus (DPF) is a machine that produces, by electromagnetic acceleration and compression, a short-lived plasma that is hot and dense enough to cause nuclear fusion and the emission of X-rays and neutrons. The electromagnetic compression of the plasma is called a pinch. It was invented in 1954 by N.V. Filippov and also independently by J.W. Mather in the early 1960s.
On November 14, 2008, Lerner received funding for continued research, to test the scientific feasibility of Focus Fusion. On October 15, 2009, the DPF device “Focus Fusion-1” achieved its first pinch. On January 28, 2011, LPP published initial results including experimental shots with considerably higher fusion yields than the historical DPF trend. In March, 2012, the company announced that it had achieved temperatures of 1.8 billion degrees, beating the old record of 1.1 billion that had survived since 1978. In 2016 the company announced that it had achieved a fusion yield of .25 joules
LPP fusion sends out reports of their progress almost on a monthly basis. The latest report is from August 15, 2016.
LPP fusion has gotten by on a total funding of about $2 to 5 million.
If LPP is successful with their research and then successful with commercialization they will achieve commercial nuclear fusion at the cost of $400,000-1 million for a 5 megawatt generator that would produce power for about 0.3 cents per kwh instead of 6 cents per kwh for coal and natural gas. It would be a game changer. Their monthly reports have shown that there are many technical, material and theoretical challenges. LPP has shown a lot of grit and ingenuity to overcome challenges.
Currently shots (test firings) are cleaning remaining impurities from the machine and it may take quite a few more, 100-200, to get to the purity level they need. They think if we get to that purity level and get 10 Joules of fusion output, they’ll have the results they need to get the investments they need for future work. Roughly, it will take about $150,000 to fire 200 shots.
They have raised the funds for 20 of the shots and performed those tests. Impurities are going down and fusion yields are increasing.
August 15 update
A new analysis of LPPFusion’s experimental results with the FF-1 device shows that fully 20% of the input energy was concentrated into the pinch region, where fusion reactions occur. As much as 12 kJ out of the capacitor bank’s initial 60 kJ was compressed into the pinch. These results, obtained in June with tungsten electrodes and pre-ionization, are about twice as good as the best ones obtained earlier with copper electrodes. The analysis was based on the device’s measured current and the voltage measured across the electrodes.
The significance of this result is that it implies that with higher current, nearly all the available energy can be transferred to the pinch. The energy available in the pinch is proportional to the square of the current, so with a current of around 2.8 MA, instead of the present 1.1 MA, energy into the pinch could be increased to 80 kJ, which is almost 70% of the maximum energy that can be put into FF-1. While a high efficiency of energy transfer into the pinch does not guarantee net fusion energy output (high density is also required, in addition to the high temperatures FF-1 already achieves), it is necessary for the net fusion goal.
How can FF-1’s current be increased? One step is relatively easy—the LPP Fusion research team can put back into use the full 12 capacitors of the device, up from the presently-used 8 capacitors. (The team has put off doing this for now, because this puts more stress on the components and allows fewer spares). Another step, shortening the electrodes, is already planned. Shorter electrodes have less inductance—a measure of how much magnetic field energy is created for a given amount of current. Less inductance means more current for the same amount of stored energy.
But to get to the full planned current of 2.8 MA, the inductance of other parts of the FF-1 circuit must be reduced, so more energy is available inside the vacuum chamber, and less is wasted in magnetic field energy outside the chamber. The research team has some concrete ideas of how to do this, but we need help in testing them out. LPPFusion needs paid help from someone who has done 3D modeling of pulsed power circuits and has present access to the software required—such as COMSOL. If you have these specialized skills, or know someone who does, please get in touch with us and we can give you more details and solicit a proposal.
Tungsten electrode tests
For the past month, the research team has been preparing for a second and final series of experiments with the two tungsten electrodes, before moving on to the planned combination of tungsten cathode and beryllium anode later in the fall (see next story). In the course of these preparations, we’ve come across a possible route to removing the tungsten oxides layers that have increased impurities in the plasma. Work by Alenka Vesel and colleagues at the Jožef Stefan Institute, Ljubljana, Slovenia showed that simple microwaves can remove the oxides. The microwaves heat a hydrogen fill gas to 900 C allowing the hot hydrogen atoms to react chemically with the oxygen in the tungsten oxide, forming water vapor. As the reaction occurs, over the course of 10 seconds, the water vapor can be pumped out, preventing the oxides from re-forming when the gas cools.
LPP Fusion Chief Scientist Eric Lerner is not certain this method will work as the microwaves will not be evenly distributed in FF-1 vacuum chamber, so uneven heating may lead to uneven oxide removal. “In your microwave oven, which is heated by the same device, a magnetron, that we’ll be using, heating is evened out by a rotating turntable. But we don’t have that in FF-1’s vacuum chamber,” he explained. But the new method is certainly worth a try and will be tested in September.
Safety Procedures, Instrument Design Paves Way for Beryllium Anode
The next step beyond the new experiments with the existing tungsten electrodes is the installation of the beryllium anode, expected to arrive in September. This will be the first time that a beryllium electrode has been used in any plasma focus device, an idea covered by LPPFusion’s patents. While most work is still concentrated on the all-tungsten experiments, the LPP Fusion research team is also getting ready for beryllium. As a light metal, with only 4 electric charges per atom, beryllium will produce hundreds of times less impurity impact on the plasma than tungsten does, for equal energy inputs.
Beryllium metal by itself is harmless, but unfortunately beryllium dust is highly toxic to many people. So the first task was consulting with beryllium experts to find out the safest methods for handling even the tiny amounts of beryllium dust that may be produced by firing FF-1 with a beryllium anode. The good news is that beryllium dust will only be produced within the sealed vacuum chamber, where the dust can be safely flushed out with nitrogen. The dust will be trapped in HEPA filters, which will eventually be safely disposed of with local hazardous waste firms. To be doubly sure, we will probably install a sampling chamber so that a sample of the gas in the chamber can be checked at a local lab for dust before the chamber is opened.