What is Fusion?
Fusion is a nuclear reaction where atoms are joined or ‘fused’ together to form a larger atom. In contrast, nuclear energy is currently generated using fission, whereby two large atoms are split into two smaller atoms. In either case, energy is generated using Einstein’s famous equation E=mc2
What is BORON?
Boron is an abundant material that can be mined in large volumes. Some applications are in glasses for composites (fibreglass), cookware (borosilicate glasses were originally made popular by Corning in their famous product ‘Pyrex’) and insecticides (Borax).
What is BORON-11?
It is a stable isotope of Boron that makes up 80% of the Boron found in nature. It can be found in open-pit mines.
What is aneutronic fusion?
It is a form of fusion power in which the energy released is carried by charged particles. It is an attractive means of generating energy, as charged particles are easier to convert into electrical power. It doesn’t create high energy neutrons, which are difficult to contain and are responsible for many of the hazards associated with other nuclear reactions.
What is the HB11 reaction?
Also known as Proton-Boron Fusion, it is an aneutronic fusion reaction denoted by the following formula:
How does HB11 Energy create electricity?
The HB11 Energy reaction creates alpha-particles, which are positively charged helium particles. These particles are neutralised when they come into contact with our reaction sphere, generating current.
This is a nuclear reaction… is it safe?
Yes, the energy generation is safe. There are no radioactive waste problems and no risk of reactor-melt-down.
How big are these generators?
As our reactor concept generates electricity directly, it does not require steam / gas turbines and electrical generators. Therefore there is no large-scale cooling or radiation shielding requirement. They have much lower infrastructure costs and a smaller plant footprint compared to conventional nuclear or fossil fuel power plants. This makes them amenable to a modular design.
How big aFusion has been 10 years away for the last 50 years… is HB11 Energy also ‘only 10 years away’?re these generators?
Significant net energy output is closer than other fusion approaches. The laser ignited HB11 reaction has been observed as an avalanche reaction achieving reaction gains of more than 109 higher than predicted (relative to simulations using classical spherical compression) [5, 8].
What is the importance of the CPA? Are there any other laser advances in the works that might further help in producing higher-powered lasers?
The important aspect of the lasers is that they have a very high peak-power in a single pulse. This power is in the order of a KJ delivered in about 1 pico or nano-second. CPA or “Chirped Pulse Amplification” describes the method by which the light is amplified, which is difficult as such a high power light easily damages optics.
The importance of the high peak-power is that we are using the lasers to accelerate particles from the target, as a result of electromagnetic fields from the light. If it is a slow pulse, the sample will heat up or disintegrate before the particles are accelerated.
The laser field is moving very quickly (think semiconductors in the 80’s and 90’s), especially this niche of CPA lasers.
Are there any advantages/differences in using Grates or Prisms to achieve the Laser Amplification?
Yes. Prisms can only be used with small i.e. low power laser systems. The reason is that the prisms can be damaged by the amplified pulse when the light passes through. In contrast gratings can handle far more power as they are a reflective optic.
There are some laser systems that are a hybrid i.e. where a prism is used as the stretcher (to stretch the pulse) and a grating is used after the amplification as the compressor.
Is the Petawatt Power of the Laser sufficient or is higher power required?
We’re not sure yet, but it is likely that we will need less. Unlike thermal fusion,where the aim is to reach higher temperatures using more power, we want to land our accelerated protons in the 600KeV peak in the hydrogen-boron fusion cross section below, which is readily achievable. Higher than that we may have other reactions occurring.
Is the role of the Laser just to initiate the reaction? Or it is also required to sustain the reaction, if yes then at what frequency does it need to be operated?
Initiate, which then will expect that it will progress via an avalanche reaction. Note that this avalanche reaction will be over in likely a time frame of nanoseconds. After one pulse of a fuel rod we would need to reload for the next pulse.
Is the capacitor coil required to generate the one kiloTesla magnetic field a mature technology or it needs to be validated?
No, but it has been demonstrated. Advancing this field will be a stream of our research.
What is the importance of the Boron source compound? Is there any advantage that Boron nitride presents?
As it is a nuclear reaction, the chemical structure is not important, but the composition is – we need both B and H. Boron nitride is nice because it can hold hydrogen and it is easy to make.
What are parameters that are important to get scale? In the case of the Magnetically confined Fusion, the size of the Tokamak determines the energy output. Are the power of the laser, the intensity of the laser, the amount of fuel, magnetic field due to the capacitor some of these parameters?
Reactor size will have no effect on us – it is important for tokamaks in order to get their plasma to very high temperatures required for thermal fusion.
It is likely that our fuel pellet will be an optimal size which is ignited by a single pulse of the laser. Therefore scale will be limited by the rate which we can reload. It is likely that scale for larger production could be achieved by having multiple reactors, even if they are all run off the same laser. In such a design, pulse rate of the laser will be important.
What is the importance of “Net-energy-gain” or “G=1”
Someone will likely win a Nobel prize when they demonstrate fusion net-energy gain with any fusion reactor. Achieving this with the HB11 reaction will be a much bigger deal given its advantages over deuterium-tritium fusion (clean, safe, abundant fuels, no radioactive waste), which is the focus of almost all other groups.
What is the yield of the alpha particles per steradian that would be required to achieve net energy gain?
As a back of the envelope calculation:
WL=laser input energy [J]
Wa=alphas output energy [J]
Na=number of alphas measured experimentally in laser hydrogen-boron11 targets for the reaction p+B11 gives 3a+8.9 MeV energy.
- Wa=(8.9MeV/3) Na=4.7×10-13 Na [J]
- G= Wa/ WL
For example, assume WL=100J
- G=1 (breakeven) requires Na=2×1015 = 1.59×1014/sr
- G=100 (reactor) requires Na=2×1017 = 1.59×1016/sr
The best that has been achieved by the few demonstrations is just short of 1011/sr. Given that there has been no attempts to optimise this e.g. by optimising fuels, the lasers, the avalanche reaction or introducing the magnetic field, this is a very high number and awfully close to G=1 (only ~3 orders of magnitude away) relative to other fusion approaches. Essentially, how we can reach G > 1 (hopefully >>1) via this optimisation is what our experimental program will discover.
How would alpha particles be converted to electricity? Will it be DC or AC? If DC, is conversion to AC for integrating to the grid a challenge?
Partly by their neutralisation in contact with the sphere, and partly by their motion as charged particles that are moving towards the sphere being held at a voltage. This would essentially be pulses of DC. There absolutely would be challenges in transforming this to AC, although it is will be much more of an engineering challenge when we design the reactor rather than a science project.
What is the importance of Avalanche reaction? Can this mechanism be controlled or is it an intrinsic property of the reagents?
It has been observed, so we know it exists, but it is little understood.
It is very important as it will likely gain us some orders of magnitude in our quest for net-energy gain (G=1)
TAE also uses p-B11 fuel. How is their technology different from HB11’s?
It is completely different (although impressive engineering!) – they are using a thermal approach. We are using a non-thermal approach. The issue with a thermal approach is that the temperature they need to heat HB11 fuels to the order of billions of degrees to achieve reactions. Given no-one has reached G=1 for D-T reactions (which only need millions of degrees) the HB11 reaction using a thermal approach is a much bigger challenge. We wish them luck!
How is the energy of the outgoing alpha particles related to the amount of electricity generated? Does higher energy imply more electricity generation? What is the mechanism of this conversion of kinetic energy to electricity?
That is what we are trying to capture. The mechanism is described in 13, and also the Roadmap paper.
In terms of energy input are there any other factors apart from the Lasers?
Lasers are the primary energy input. The next consideration will be the energy required in producing the fuel pellets, which we expect will be less than the pulse.