A Look At US Fusion Research
US Fusion Budget: The US fusion budget last year was 951 million dollars [1]. For comparison NASAs’ budget was eight billion [2]. I argue that the current fusion budget is very low and lopsided. It is lopsided because it focuses only on two approaches - which we know will not become commercial. It is low, because this budget gives us no space for anything new. Sadly, this has been the state of things for about the last 20 years or so. Below is a plot of the US fusion budget.
Laser fusion (ICF): The US fusion budget gets split in half. Half of the money is sent out to support laser fusion and related technologies. The main goal of that money is to maintain the status quo. It holds up activity at the national labs, a few companies and a few universities. Laser fusion is where you take a small ball of ice and you blast it. The ball of ice is frozen radioactive hydrogen. The beams attack from multiple (60 or 192) directions and squash the fuel [3, 4]. When the beams hit the ice surface, there is an explosion of energy outwards and an equal and opposite compression wave inwards. This compresses the fuel to a temperature and pressure where fusion can occur. For example, a typical temperature could be between 10 and 15 million degrees kelvin and the pressure is 1000x the density of water [3, 4]. A typical implosion would last about 20 nanoseconds. This laser approach to fusion is over sixty years old [5]. For the first ten years it was classified by the US government. The effort became public in 1972 [6]. Since then we have built a couple dozens of these kinds of machines. The government likes this approach because aside from doing fusion you can replicate the environment inside a nuclear bomb. I spent six years working on this fusion approach. My doctorate was on developing these ice balls – known as targets - trying to find ways to create them in a cheaper way.
A picture of the National Ignition Facility – a very expensive ICF system. The biggest laser facility in the world is the National Ignition Facility. This machine was built at Livermore National Labs. Construction started in 1997 and it took them 12 years to build. The thing cost 3.8 billion dollars and was first turned on in 2009 [3]. The key idea behind NIF was getting something called ignition. Ignition is a fusion chain reaction. You get 1 fusion event, and that creates another, and another, and another. That is a big deal - if you can make it to work. Well, in 2016, the Department Of Energy admitted that NIF will never ignite [7]. That was a big deal. What it means is that laser fusion is probably not going to work as a power plant approach. You cannot get enough energy out of the machine to overcome the huge energy you put in. NIF is probably somewhere between 3 and 0.5% efficient [8]. Moreover, this is a major defeat more than just one approach. There is a whole family of laser fusion-like approaches that are very closely related. Some concepts include: direct drive, indirect drive, ion drive fusion and fast ignition [9, 3, 4, 10]. All of these ideas suffered with NIFs’ failure to get ignition. So bottom line: we are spending 440 million on a spectrum of groups, companies and universities following an approach that we know will never work. It will not work energy-wise nor will it work commercially. That may have been fine when there were no other fusion approaches available to us – but that is no longer true. Tokamaks: The rest of the US fusion budget goes to a family of magnetic schemes surrounding the tokamak. A tokamak is basically a racetrack. If the ions are the cars, then the course is set by the magnetic fields. The ions race around, and around, the ring. Hopefully they bump into one another at high speeds. When they do this, they can fuse. The tokamak is the world-wide fusion research heavyweight. Over 220 tokamaks have been built, planned or decommissioned since this field got started [11]. Today, we are reaching a point where 80% of all the fusion researchers in the world - are all tokamak people. That is a problem. The program directors, the reviewers and the university professors are mainly looking at fusion through the lens of a tokamak; through the physics of a tokamak. This means they have a mostly hazy understanding of other approaches. Not to say that tokamaks have not worked well. For example, the world record for the longest running tokamak is 26 hours. That was set by a startup in England [12]. Technically, the world record for energy extraction, in fusion, is held by a tokamak. The record was set by a machine called JET, in England in the late nineties. That record? 23 percent. That machine took 100 megawatts to run [48] and it pulled 23 megawatts out of the plasma. It is worth pointing out that the JET team claimed a much higher efficiency. But, they were playing math games (NIF did the same thing in 2014). They used the energy on plasma as their starting point – not the real input numbers. Finally, a good example of a typical tokamak performance was set by China. They ran their machine for 102 seconds at 50 million degrees [13]. That is considered very strong showing in the tokamak world.
A picture of the ITER site. Right now, the world is building a huge tokamak in France, called ITER. This project is the focus of most of the US fusion effort. ITER work is being done in many states across the US. Multiple companies, organizations and universities are involved. Ultimately, we don’t know how much this is going to cost, but estimates range from 16, 21 and even 50 billion dollars [14 - 17]. Currently ITER is 7 years delayed [18]. I suspect that it will be NIF all over again. They will finish it. It may work - or it may fail physically - but it will never work commercially. I doubt it will produce more energy than we put in it. We heard this same story for 12 years with NIF – and that machine failed. There are basic flaws with these huge machines. It takes so long to build them - that innovations cannot be added as construction occurs. They are also very complex – hiding problems within the technical details. They also rely on models that can make assumptions that turn out to fail. That said ITER will drive technology into the greater economy – even if it fails. Amateur Fusion: Since 2000, fusion has been moving in new directions, which I think are worth watching. These are outside of the federal system. New innovations have come from two groups: amateurs and venture capitalists. I will start with the amateurs. The first private citizen to build a fusion machine was a guy named Richard Hull. He was living in Richmond Virginia and in 1999, Richard built a small fusor in a shed behind his house. He got fusion. This was a pivotal moment in the history of fusion – and almost no one noticed. It paved the way for people to start doing fusion in their homes. A fusor uses an electric field to heat ions to fusion conditions. Typically you need between 10 and 110 thousand volts to make them work. They have a big metal cage in the center. This sucks away mass and energy from the device. Typically the losses are 10,000 to 1. Meaning, for every unit of energy of fusion we make we are losing about 10,000 to that wire cage [38].
Since 1999, amateur fusion has grown significantly. About 90 people in North America have built small fusors in their homes and garages. Some are just middle school kids. Jamie Edwards is one example. He fused the atom at 14, in his middle school, for about 2,000 dollars. They had him on The David Letterman Show a few years ago. I mean, when a 14 year old can fuse the atom in his school, the world needs wake up the heck up and realize that something big is happening here. Fusors work. They can run continuously. I have heard it said that you could run one for days without a problem (though I have never seen it done). In 2015, we even had an amateur claim that he got 1E11 fusion reactions per second on a 100 watts of input in a fusor [37]. That is about 100x better than a typical fusor, but not strong enough to get excited yet [38].
We have now seen amateurs build other devices, other than fusors. To be clear: none of these machines have gotten any fusion yet. But, we have seen an amateur field reversed configurations [36], amateur spindle cusps [34] and I know of one group trying to build an amateur compact stellorator [35]. These are all unique fusion machines – devices we’ve never seen outside of university labs – being built by hobbyists. The reason for all of this is pretty simple. Amateurs can do this now because of superconductors. That technology has now reached a point where you can get a strong field, for a reasonable price and a small electrical energy. In the case of high temperature magnets, you can run them at reasonably cold temperature using liquid nitrogen. Often times, these kids can get the stuff they need for free. The companies are willing to hand over the magnets for free.
Venture Capital: The other group to watch is in fusion are the Silicon Valley folks. There are about a dozen startups who are explicitly chasing a fusion concepts. They maybe have 2 to 3 hundred employees between all these companies [39]. The two biggest ones are General Fusion and Tri Alpha Energy. Between them, they have raised about a billion dollars in private capital. General Fusion was founded in 2002 in Vancouver Canada. Their approach involves getting a plasma donut into a spinning bath of lead-lithium and compressing the fluid around it. They have raised money from famous investors like Jeff Bezsos. The company has been making a lot of headway both technically and publically. That said, I was disappointed in the latest results they shared at the ARPA-E meeting in August [40]. As I understand it, they want to scale to a bigger machine, which I see as a bad sign.
The other big company is Tri Alpha Energy, which has a partnership with Google [42]. The company has gotten funding from Peter Theil and Steve Balmer from Microsoft. This company dates back to 1998 and it has an approach based on the field reversed configuration [41]. The FRC is a self-sustaining plasma donut. The plasma moves in a loop. That movement makes a magnetic field. That field self-sustains the donut. The FRC is an example of a self- organized plasma. I think self-organized plasmas are the direction this whole field needs to move in. The FRC is great. The problem with it is stability. The loop slows, and flies apart. Tri Alpha has to keep its’ plasma spinning by hitting it with particle beams along its’ surface. Like the old game of the hoop and the stick. Last I heard, they were able to keep the donut spinning for 11 milliseconds [43]. That might not sound like a long time, but this was kept moving for the lifetime of the machine. Meaning if they build a machine that can run for 2 hours, they may get 2 hours of fusion.
Behind these two big companies, there are about a dozen smaller groups. I like CT fusion from the University of Washington. I like EMC2 which just did some groundbreaking simulations on the polywell. I also like Lockheed Martin’s CFR machine, but I urge them to publish. I also think Tokamak Energy is doing very well. There are more groups that need to be watched.
Fusion, On The Market Finally, I want to mention that there is now a commercial product on the market that uses fusion. For a bit over a million dollars, you can buy a neutron generator from a company called Phoenix Nuclear Labs [45]. Neutron generators based on fusion are not new. We first saw them on the market back in 2000, from a company called NSD-Gradel. But this PNL machine is lightyears ahead of where they were. The device can produce 1E+11 neutrons per second, for over 130 hours continuously [44]. Along with another company, PNL is gearing up to use these devices to mass manufacture medical isotopes. That market is about 1 billion dollars a year worldwide, and these companies are going to crush it. They signed a 110 million dollar deal with GE Health care and a distribution deal with Chinas’ largest pharmaceutical company [45]. In August, Shine broke ground on a new facility to manufacture these isotopes [45]. I’ve heard it said that fusion power has the potential to give us limitless free energy one day. In your opinion, how likely is that to happen and how far off might that be? The milestone in front of everyone is net power. That is like that first lift off at Kitty Hawk. No one has done it yet. Not in sixty years. Not anywhere in the world. We have known since 1956 what it will take to get there. A British man named John Lawson is too thank for that. In 1956, John worked out the energy balance for any plasma-based fusion device [28]. Here it is below.
All you got to do is build a machine to beat this equation and you’ve made history. Net could mean 101 watts out of a 100 watt input. All it means is more energy out than you put in. I have written extensively about each term in this equation, and what kind of design principals it means for a fusion device.
Fusion rate is self-explanatory. So far, much of the world has focused solely on this, by driving at triple product.
Conduction. This is all the energy that leaves with the mass. Metal is the enemy here. When plasma touches metal - it leaks out. This robs energy from the machine, killing it’s’ efficiency. Hence you need space around your plasma. You also want a strong trap to keep the plasma away from the walls. Lockheed Martin is following a long shot approach to make a near perfect magnetic trap – which if it works – would be a big break through [29 -33]. Foolishly, Lockheed has not published so we do not know where they stand. I have even seen people build their chamber out of insulators like glass to stop conduction losses [25].
Radiation. This is all the energy leaving the plasma as light. Plasma bleeds energy away, as light. People have talked about reflecting that light back into the plasma – but that idea is very, very limited. For example is almost impossible to reflect an X-ray. Another option is to drive up your density. That could slow light loss. Personally, I think your best bet here is trying for a tuned plasma. In a perfect world you would want a plasma with lots of really cold electrons and a few hot ions. That would be best. This kind of distribution may not be possible [29]. It is not clear at this point. Energy distributions in plasma are a function of many other things: shape, structure, magnetic and electric fields, injection, runtime, ect…. Could you tune your plasma? IDK. We need to get hard data proving this one way or the other.
Efficiency. This is how well your device spends or collects energy. There has been some exciting work done here. In 1982, a team a Livermore was able to capture 48% of the energy coming off a fusion reactor using something called direct conversion. Basically direct conversion works by putting the charge particles coming off the reactor directly into a wire. When will fusion happen? I cannot say for sure. But I can say that impossible problems have been solved in the past. 150 years ago, human powered flight was considered impossible. Every expert said it could never be done. The general public saw it as impossible. Meanwhile - in the background - a small group of innovators were trying everything they could. All kinds of wild ideas were tried. Lots of failures happened. No one was paying attention. And then, suddenly, two guys who did not have a formal education and whom no one had ever heard of, created flight. So impossible problems? Sometimes they can be solved.
Could fusion power be a workhorse for moving man into space both cleanly and cheaply? Yes, I think fusion could have a major impact on spaceflight. There are two basic plans for a fusion driven rocket. In plan one, you put a fusing plasma at the apex of a parabola, at the back end of a ship. This material escapes the fusing core at high speeds, bumps against the ship wall and shoots off in one direction. This pushes the ship forward. In the second plan, you have a cavity at the back of the ship. Plasma get sped way up as it passes by a fusing core. The plasma has to shoot through a tiny hole in the back. As it does it flies out very quickly.
An example of both basic fusion rocket approaches. There are currently a few NASA funded efforts to look into this:
The University of Maryland got some money to look at using a fusor as a space engine. A company called MSNW has raised about a million dollars to try to do this with a field reversed configuration. A company called Princeton Satellite Systems has a 500K grant with Sam Cohen a Princeton professor who has built a rotamak. Sam has the world record for the longest stable FRC ever created (300 milliseconds). They predict 100 kilometers per second of thrust. This could get you to Mars in a matter of weeks. References:
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