Part 2 of 2 Parts (Please read Part 1 first)
Research plasma railguns are typically operated in a vacuum and not at ambient air pressure. Plasma railguns are valuable because they can produce muzzle velocities of up to several hundred kilometers per second. Because of this characteristic, plasma railguns have applications in magnetic confinement fusion (MCF), magneto-inertial fusion (MIF), high energy density physics research (HEDP), laboratory astrophysics, and as a plasma propulsion engine for spacecraft.
Linear plasma railguns put extreme demands on their insulators because they must be an electrically insulating, plasma-facing vacuum component which can survive both thermal and acoustic shocks. In addition, a complex triple joint seal may exist at the breech of the bore. This can often pose an extreme engineering challenge.
The NearStar nuclear fusion reactor has rails which are about a hundred feet long. They fire a fuel capsule with a mix to deuterium and tritium gas at six mile per second into a twenty-foot square reaction chamber. An approximately two-foot field coil with a small hole in the center is located inside the reaction chamber. As each pellet of fuel passes through the hole in the center of the coil, an extreme magnetic field crushes it and produces a flash of fusion. A heat exchanger circulates a liquid molten salt through the walls of the fusion chamber which is heated by each fusion reaction. The heat exchanger produces steam which spins a turbine to generate electricity. Improvements in the design of the plasma railgun could allow the future use of advanced fusion fuels, lowering cost and improving efficiency.
In addition to its use in commercial fusion energy reactors, the plasma railgun could be used as a test bench for the development of advanced nuclear fusion propulsion systems for spacecraft.
There is another advantage to the railgun approach. If nuclear fusion is achieved via inertial confinement with laser bombardment, the use of high-end lasers will require that highly technical staff will have to operate the power plant. On the other hand. NearStar believes that a powerplant that uses railguns could be operated by upskilled car mechanics and maintenance workers. This would definitely be a better proposition from a commercial perspective.
NearStar has a handful of people but it is expanding its team to include scientists and engineers. It aims to break even in the next five years. Amit Singh is the CEO of NearStar. He previously worked in a data analytics company. He believes that all the components needed to make commercial nuclear fusion a reality are available. He thinks that the company’s simple approach will help reach that goal sooner rather than later.
Singh said, “What's unique about NearStar is that everything we need to build the fusion power plant already exists on planet Earth. So, in a lot of ways, we're kind of like the Wright brothers — we shouldn't be the first to flight, but we think we will be because our design and our architecture are so much more simple.”
In the future, nuclear fusion plants will get smaller. It will be possible to build them under buildings and reduce transmission and distributions losses.