Originally Published On January 18th 2015, on The Polywell Blog. Author: Dr. Matthew J Moynihan
ITER is expensive. Nobody knows how much. It could be 16, 21 or 50 billion dollars [9-12]. It is not going to be commercial at that price. Moreover, ITER will never make energy. That was fine, when it was the only path to fusion power. But that is not true anymore.
NIF has failed. It cannot get ignition . Even if it could, would it be commercial? The machine is complex. It is expensive and inefficient. Heaps of taxpayer dollars were spent on this. The public should be furious. Someone needs to be held accountable.
These efforts have stalled. Their future looks dim. But, we cannot wait fifty years for fusion power. Climate change will not allow us. Young fusioneers realize this. They are not joining ITER or NIF. They are joining a new breed of companies. Together, they are building an entirely new fusion industry. Their collective hope, is to put a dent in the universe.
“We’re here to put a dent in the universe, otherwise why else even be here?” – Steve Jobs
Traditionally, fusion has focused on any idea in the laser or tokomak family. Laser fusion means inertial confinement fusion. This includes: direct drive or indirect drive, fast ignition or magneto-inertial fusion . Basically, any time you are squashing stuff with a laser. This set of ideas has received over 12 billion in US funding in its’ fifty year lifespan . Currently, it has a poor outlook. The flagship machine, NIF, was costly and complex. It was also a colossal failure . The other family of ideas revolves around the tokomak. The tokomak family covers: spheromaks, the levitating dipole and all the stellerator designs [56, 57]. Basically anytime plasma is raced around in a loop. Over 177 Tokomaks have been built, designed or operated. The newest version, ITER is very expensive, complex and behind schedule . Things are not going well. Even attempts to commercialize the Tokamak are not succeeding. Tokomak Solutions is a British startup doing just that. It was founded in 2009 . But, after spending 10 million, the company is little more than a diversion for retired scientists. The staffs’ average age is over 60 [58 - 63]. They speculate about using the Tokomak as a neutron source. If this is their business model - they are going to get killed. Phoenix Nuclear Labs already has a smaller, cheaper and better product based on fusors. PNL has had this product for over five months . Bottom line: tokomaks and lasers are on their way out.
This is a historic. For decades, our focus has been on just “getting there”. Merely getting fusion. This meant holding a hotter plasma with a higher density for longer. This is known in the field, as the triple product (density, temperature and confinement time). People ran roughshod over price, scalability, efficiency or size. No one cared: they built massive, expensive and complex machines. But today; we have arrived. We can do fusion - continuously - for thousands of hours, and for thousands of dollars [35, 22]. We are done with “getting there”. The next step is commercialization.
The alternative fusion industry:
Since 2000, a dozen fusion companies have been founded [73-105]. Together, they represent a fledgling new industry. The alternative fusion industry. What does this industry look like? I estimate that as of December 2014, it has roughly 450 million in total investment [73-105]. It also engages roughly 330 people [73-105]. These people are spread across fourteen organizations. A summary of some of the relevant groups is below [73-105].
In total, the industry spans seven different technologies. Because it is so new - the industry suffers the classic “first-mover” disadvantages. We have find a way to get funding, train talent and solve incredible technical problems. The firms have lots in common: determined founders, failures and funding issues. Our collective goal is fusion energy - but we have differing views on how get there.
How we (might) get fusion power
All these concepts work with plasma. This is a soup of electrons and ions. The goal for every ides is to make the ions collide and fuse. This makes neutrons. The more neutrons, the more fusion. Amateurs can make a million a second [22, 23]. Phoenix Nuclear Labs can do 100 billion while JET can do at least 16 quadrillion (the world record) [24, 65]. Next, you must sustain fusion. This “shot time” is driven by containment. Focus fusion argues that all they need is a nanosecond for net power, while General Fusion is aiming for hundreds of microseconds and Tri Alpha Energy says it can do 5 milliseconds [30, 31, 66, 67]. But who knows? Mr. Griengers’ homemade fusor can fuse for hours at room temperature [22, 23]. Could the polywell give the same behavior? Dr. Park has suggested it; especially if the plasma can be heated steadily .
Once you contain the hot plasma, you must extract energy. Not every team has planned this far. General Fusion wants to absorb everything in a liquid blanket, heat it and make steam . Focus fusion has suggested a traveling wave tube . Polywellers have pushed for a form of direct conversion. Both of these ideas are shown below.
Here is how these ideas work: exhaust from fusion is a mixture of neutrals, ions, electrons and gas. It is a mess. It comes off in all directions. It comes off at many speeds. First, we must beat this stuff into submission. Ideally, we only want a beam with one kind of charge. The traveling wave tube uses a positive beam. Ions fly down the center. The pull electrons from the surrounding wire. This makes a flowing current. Direct conversion puts metal in the way of the beam [127 - 129]. Ions are absorbed – holding one side of a circuit, steadily positive. You can draw a current from this. Several teams have discussed using this [20, 122]. But, though we can do relatively cheap fusion, for hours [22, 23, 35] no team can steadily draw a current from fusion for that long. Not yet.
The Energy Balance:
What comes after energy collection? Optimization. That will revolves around the energy balance. Any hot plasma concept must grapple with this equation.
John Lawson gave us this equation in 1957 . It is the energy balance for a machine fusing with hot plasma. We have always merely tried to boost the first term: fusion rate. But we may finally be changing focus. The next term is conduction. This is the loss of mass. Anytime a plasma touches a surface, it is lost. The newest designs (polywells, Lockheeds’ machine, the dynomak, Phoenix Nuclear Labs’ device) all appreciate this. They all have smooth surfaces - and some cases, no surfaces at all. Both PNL and the polywell have vast space in the center [1, 24]. Space without a solid wall limits conduction loss. After this comes radiation. If a particle ever changes speed, it loses some energy as light . This happens everywhere inside the cloud, and for many reasons. Radiation is a function of cloud composition, temperature, density, size and structure. Fusioneers are just starting to tune their plasmas to beat this problem. For example: the polywell works best with tons of cold electrons, and a few hot ions .
Can this distribution be done? We do not know – mixing and instabilities will fight against it . But, it is possible to make plasmas which do not have the common bell curve [25, 110]. Tuning plasma clouds to beat radiation loss is going to be important. Finally, there is machine efficiency. Most fusion machines are very inefficient. NIF is one example. It takes 200 units of electrical energy to make one unit of laser energy . Most of that does not strike the target. New methods for energy capture will go a long way here. Realize: if the energy balance was correct; even the fusor could make net power.
New Design Principals:
Wither they know it or not, these groups are embracing a new set of design principals. Principals that have emerged in the past 10 years - outside tokomaks and laser fusion. I argue that history will see this as a turning point in fusions’ development. Below are these principals.
1. The Blob is Death. In 1994, Todd Rider assessed the polywell theoretically and came to conclusion it would fail [5, 106]. This post can walk you through his work . Rider did something even more profound, that few appreciate. He told us what not to do. He showed that if you merely have a hot plasma blob, you cannot expect net power. A “blob” is a hot, thermalized, uniform, unstructured cloud of ions. The blob is death. Anything you can do to get away from the blob, helps. This includes squeezing the plasma (ICF, General Fusion, Sandias’ Z-machine) spinning the plasma (Tri Alpha Energy, ITER, JET, Helion), flattening the plasma (focus fusion, theta pinch) or structuring the plasma (polywell, Lockheed). The further from the blob, the better.
2. Electric heating. You can accelerate ions down a negative voltage, heating them to fusion temperatures . Today, this is the cheapest and simplest method for heating to fusion. This is arguably far better than options like radiofrequency heating, neutral beam injection or magnetic oscillation. Radiofrequency heating works in the same way that a microwave heats food [21, 27, 28]. Beam injection starts by heating the gas; by temporary charging it and racing it down a voltage . The beam is then neutralized and shot into the reactor. Magnetic oscillation (as I understand it) varies the field around a plasma. Lockheed is notably following this last path [21, 27, 28].
3. Cusp confinement. You can hold a plasma with a sharply bent magnetic field [1, 133-135]. This has been long predicted – but never seen until Parks’ work . There are many unknowns, but if it is successful - it may lead to the worlds’ best plasma trap. In these systems, the plasma “pushes back” the containing field. This makes to a magnetic free region with an electric current flowing on its’ skin [133-135]. Theoretically, this structure is stable; but who knows? There are a myriad of instabilities which could destroy it . We may know more when Lockheed publishes what it has learned on this system [21, 27, 28].
4. Direct conversion. Direct conversion has been discussed for decades. The trend of incorporating it directly into designs is what is exciting. This was tested on the TMX fusion device and it achieved a 48% efficiency .
Where will all this take us? No one knows. These firms are expanding several root technologies simultaneously. These are: polywells, fusors, dense plasma focus, beam fusion, field reversed configurations and cusp confinement. These technologies have plenty of overlap. For example: general fusion has a hybrid between a field reversed configuration and a laser fusion style implosion . Below is a summary of commercial funding by concept [73-105].
Fusion is changing. We need to stop seeing a hodge-podge of technological novelties and start seeing it as a new industry. An industry where innovation is happening much faster than in “big science”. An industry which must consider price - because it does not have an ITER sized blank check. An industry which is much closer to profit than you realize. Yet, an industry which still has a long way to go. In its’ success - may rest the future of the human race.