A personal note on Helion's approach to fusion energy.
Fusion energy is the energy that powers the sun and the stars. The most common fusion reaction is the fusion of two hydrogen nuclei into a helium nucleus. The energy generated from the fusion procedure arises from the disparity in rest mass between the reactants involved in the fusion and the resulting product, as governed by Einstein’s E=m.
Helion Energy is pioneering advancements in nuclear fusion technology. Their current sixth-generation nuclear fusion generator uses magnetic fields to merge two plasma rings, transforming kinetic energy into thermal energy, heating the plasma to tens of millions of degrees, thus facilitating nuclear fusion. Unlike traditional methods, Helion employs a unique process that keeps the hot fuel off the walls and utilizes pulsating high-intensity magnetic fields. This technique results in a self-confined, self-organized plasma that moves like a piston when fusion begins, efficiently generating electricity.
Moreover, Helion’s approach harnesses a more abundant and safer fuel mixture of deuterium and helium-3. They’ve develoepd a method to produce the otherwise ultra-rare helium-3. The company’s progress continues with the development of their Polaris, a seventh-generation system that’s larger and designed to begin electricity capture. Helion’s fusion technology is not only promising in terms of its efficiency but also offers hope for a cleaner and more sustainable energy future.
Different fusion processes may yields comparably high energy; however, the feasibility and efficiency of harnessing that energy largely hinge on the properties of by-product particles. These particles are pivotal in determining the challenges and practicality associated with each fusion process.
Helion uses a Deuterium and Helium 3 as fuel for the fusion process. This is different from other fusion process which uses Deuterium and Tritium such as in Tokemak. Let’s compare the two.
(I) \(D + {}^3He \rightarrow p + {}^4He + 18.3 \text{ MeV}\)
(II) \(D + T \rightarrow n + {}^3He + 17.6 \text{ MeV}\)
While process II produces similar amount of energy compared to process I, there are multiple challenges. (1) The neutron captures 80% of the released fusion energy. This is a problem for the reactor where neutrons are hard to contain (since it has no charge) and can damage the reactor at high energy. (2) Tritium (T) is quite rare. Producing it is challenging. (3) Capturing the energy from neutron and converting it to electricity requires a lot more steps compared to Helion approach.
Process I produces a proton (which is charged) whose energy can be captured to produce electricity directly. This is a big advantage for Helion’s reactor. To make this possible, Helion developed a process to obtain \({}^3He\) (which is much more rare compared to Dueterium).
Caveat: \(D + {}^3He\) does require higher initial temperature which is a challenge. This is solved via a great deal of engineering, using capacitors to capture energy and releasing them in 100 micro seconds, producing 100,000 to 1M Amperes of current.
Helion has developed a process to produce \({}^3He\), which relies on the Deuterium-Deuterium fusion. One of the possible outcomes of such fusion contains \({}^3He\), that is,
(III) \(D + D \rightarrow {}^3He + n\)
The neutron resulting from this reaction has an energy of around 2.45 MeV. This is considerably lower than the 14 MeV neutron produced from the D+T fusion reaction (process I). This lower-energy neutron is less damaging to reactor materials due to reduced neutron activation, resulting in fewer atomic displacements within the materials.
Considering this, the concept of having a dedicated reactor for the generation of \({}^3He\) via the D+D fusion process is intriguing. Such a setup would act as a buffer, ensuring the main energy-generating reactor (employing the \(D + {}^3He\) reaction) remains unaffected by neutrons. If damage does occur in the fuel-generating reactor, it could be replaced without disrupting the primary energy production.
Helion uses a magnetic field to confine the plasma. The plasma is then compressed to a very high density. This is done by using a piston-like mechanism. The plasma is heated to a very high temperature and pulsed towards each other where the final temperature reaches 100 million degrees, which then initiate the fusion process. Seems like quite an engineering marvel!
Tokemak captures the energy of neutron by slowing them down and generate heat. The heat is then used to create steam which rotates a turbine which then moves magnetic coils to generates electricity. Helion generates the electricity directly by capturing the energy of the proton via changing magnetic field, skipping many steps of Tokemak. This is really neat!
Helion is currently developing their 7th generation reactor, named Polaris. The primary distinction from the 6th generation lies in the advanced engineering designed for a higher repetition rate and enhanced energy yield. With this iteration, the company aims to achieve net positive energy output in 2024. Exciting times!
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