Academic Review 2024

56 ST EDWARD’S, OXFORD

Another popular alternative approach to fusion is the inertial confinement reactor (ICF). This involves using projectiles to compress a small target fuel cell and allow the elements inside to fuse. Unlike magnetic confinement, this method does not require the initial heating of the fuel to allow it to fuse. Inertial reactors are based solely on the compression aspect of fusion. An example of this would be the reactor developed by the First Light company in Oxford. They use a simple pressurised gas gun to launch a small projectile down a long column. A fuel cell containing two isotopes of hydrogen is simultaneously released down the column. The projectile meets with the fuel soon after in a chamber, and the collision between them creates immense pressure inside the fuel cell, permitting fusion. This extreme pressure is achieved from the shape and design of the fuel cell. First Light do not specify how this works for reasons of secrecy. The advantage this approach has over the Tokamak is that the technology required is less advanced. This makes cheaper reactors which are easier to engineer and manufacture. A difficulty with ICFs however is the rate of fusion and capture of energy can be less efficient. This is because the reaction is not magnetically confined like it is in the Tokamak. When the fusion takes place the compression of the fuel creates a rapid explosion, expanding the gas (fuel) inside the chamber. If the pressure created is not strong enough, the outwards force of the fusion may outdo the inward pressure and not allow all hydrogen isotopes to fuse. When it comes to the future of fusion, I expect the ICF approach to be the type of reactor used commercially. With advancements in technology, it seems more likely that there will be improvements in the efficiency of projectile-based reactors, rather than a reduction in price of the Tokamak approach.

There are, however, still challenges with the engineering of the Tokamak which is not ready for commercial use. The only times fusion was achieved, there had to be more energy put in than energy out. Although it is functional, it still is not economically feasible. Random plasma instabilities can disrupt its confinement, causing almost instant plasma termination due to energy loss (Kikuchi, Lackner, & Quang Tran, 2012). Fortunately, whenever the plasma does contact the walls, it loses thermal energy before it does any severe damage. Another challenge is managing the byproducts of the D-T fusion. A drawback of the D-T fusion is the 14.1 MeV neutron immitted after each fusion (Kikuchi, Lackner, & Quang Tran, 2012). These neutrons end up penetrating the reactor walls and activate the material that they are made from causing it to become radioactive and brittle, limiting the reactor’s lifespan. Long term, this can be solved by fusing different types of isotopes that have a reaction causing less neutron damage to the surrounding reactor components. In fact, the D-D reaction has a compellent aspect where there is only one reactant involved (deuterium), making it simple to fuel as other reactions with different reactants require a certain ratio between the two. D-D fusion also has a lower neutronicity, making for less damage to the structure. Although this could be a solution, D-D reaction requires higher temperatures to initiate fusion. Only future generations of reactors may be able to achieve this with advancements in superconductors capable of producing higher magnetic field strengths. “ Another popular alternative approach to fusion is the inertial confinement reactor (ICF) ”