With current concerns about the security of gas and oil supplies for Europe and beyond, the need to maximise energy generation from low-emission sources has been brought back into the spotlight. Nuclear power offers a reliable source of low emissions electricity to reduce our reliance on fossil fuels from other parts of the world, but its effects on the environment have often been called into question.
Magnetic confinement fusion provides a means for controlled fusion, without the heavy environmental impact of conventional nuclear power plants. In addition, this approach offers long-term sustainability, relying only on a supply of more readily-available hydrogen isotopes to fuel reactors.
The concept of using large toroidal magnetic fields to trap a plasma for fusion was first outlined decades ago. Extensive experimental work has been done over the decades since, but generating large enough magnetic fields to confine the plasma proved problematic.
Major technological advances, particularly in terms of the magnetic confinement, are now finally making it commercially viable. This means that:
- The barriers to entry aren’t as great as they once were.
- The timeframes needed for reactor builds to be completed are becoming a lot shorter (around 5 to 10 years, rather than 25+ years).
- Financial outlays have reduced and the return on investment can be seen more quickly.
Consequently, magnetic confinement fusion is no longer exclusively about large government-funded ventures, but is becoming a target for companies in the private sector. With an exciting new market now opening up to these companies, they want to get a competitive edge – and real-time mapping of magnetic fields to high degrees of precision provides a way of doing this.
Current magnet mapping technologies
The incumbent Hall sensor technologies used to map fields in magnetic confinement fusion have numerous drawbacks. The most important of these is that it is not possible to place them in-situ. Among the main reasons for this is that they cannot handle direct exposure to the low temperatures involved (which go down to 40-50K, because of the superconducting magnets being utilised) or the large magnetic fields. Instead these sensors have to be enclosed in warm bore inserts. This technique only works for mapping magnetic fields when no fusion reaction is taking place though.
The other option is software-based. This isn’t ideal either. Creating a relatively accurate model takes a long time, and still won’t be as good as having actual measurement data to work with. Therefore, neither of the existing techniques are really that effective.
A new unique strategy
Paragraf GHS sensors are robust enough to work at cryogenic temperature levels, enabling in-situ measurement. Our sensors cover a wider Tesla range too, so different device types don’t need to be employed in different parts of the reactor design. They have higher resolutions than standard Hall sensors, so smaller changes in the field can be determined. This is due to the high sensitivity of the graphene sensing element used, as well as its 2D structure (avoiding planar Hall effect issues). They also have far better linearity, and don’t exhibit sensor drift over time or have hysteresis issues.
By using Paragraf GHS sensors for field mapping, the following benefits will be delivered to reactor manufacturers:
- The quality of the data they have access to will be improved.
- Alterations to designs will be easier to implement, enabling improvements to reactor performance and greater electricity output.
- The period taken up by experimentation and calibration work will be shortened (with no need to deconstruct everything after tests have been done).
- Time to manufacture will be accelerated, with deployment starting sooner.
Once fusion is up and running, electricity generation companies will also benefit from these sensors by:
- Being able to continuously monitor their reactors in real-time, so that they run at peak power.
- Picking up on any fluctuations in the plasma, then countering them by making adjustments to the magnetic field – to maintain the confinement conditions and keep the plasma stable.
- Having access to data that will help them make better informed decisions on optimising reactor operations.
Paragraf can already draw on a successful track record of supplying graphene-based magnetic sensors to the high energy physics customers. We’ve been working with high-profile scientific research organisations, including CERN and NPL. Our devices are already being sampled by companies participating in several magnetic confinement fusion projects. By adopting our technology their route to completing reactor installations is certain to be faster.