ZEPTO: the super-charged, energy-efficient magnet hero we need!
ZEPTO might sound like a minor character from a 1950s superhero comic, but it is actually a kind of magnet that could revolutionise future particle accelerators by cutting their energy bills and their carbon footprint… OK, ‘ZEPTO the planet-conquering robot’ might sound more exciting but ‘ZEPTO the energy-saving magnet’ is kind of cool too.
Particle accelerators are important in many aspects of physics. They help us uncover a hidden world much smaller than our eyes can see, they teach us about the origins of the Universe and why the world is the way it is. Despite this, their high energy usage makes them expensive to run, due in no small part to their electromagnets.
Experts at STFC’s Daresbury Laboratory have been developing a sustainable alternative to these magnets. The Zero Power Tuneable Optics (ZEPTO) magnet is an innovative way for accelerators to reduce both running costs and carbon footprint. The magnet is now being tested at Diamond Light Source — the UK’s national synchrotron (circular particle accelerator) science facility, in Oxfordshire.
Behold the evil energy-swallowing electromagnet!
Traditionally, a particle accelerator will use electromagnets to control their particle beams. These work by flowing an electrical current through a coil of copper wire wrapped around specially shaped steel.
As the current flows through the wire, it generates a magnetic field, which is then conducted by the steel towards the beam. Depending on the experiment’s requirements (or what happens to the beam during the experiment), the current can then be increased or decreased to influence the strength of the electromagnet.
A downside to this system is, because the electrical current must be as constantly flowing to maintain the magnetic field, it can be extremely energy intensive and thus be expensive and create a significant carbon footprint. It is predicted that one quadrupole magnet on Diamond is responsible for around 136kg of carbon dioxide released per year.
ZEPTO to the rescue!
So the traditional electromagnetic is an energy-hungry beast. ZEPTO magnets tackle this by using permanent magnets to make their magnetic field, a classic example of this type of magnet is the standard fridge magnet. However, ZEPTO’s magnets are larger and made of a special type of material known as Samarium Cobalt (think ‘vibranium’ of the magnet world). Permanent magnets made from this material can be made extremely strong under the right conditions when created.
Here’s some origin story exposition
Every hero has an origin story in which he overcomes an obstacle to become the hero he was always meant to be, and ZEPTO is no exception.
So, we have a magnet with a permanent magnetic field, but what if we want to change the field strength to help our accelerator beam?
This is where the difficulty begins. Four curved pieces of steel are located inside the ZEPTO magnet, which direct the field generated by the permanent magnets to create a quadrupole. A quadrupole is a magnet with 2 north poles directly opposite each other e.g. at the top left and bottom right of the beam and 2 south poles opposite each other at the top right and bottom left.
This makes a field which is zero in the exact centre of the 4 magnets (and therefore the centre of the beam) and increases in strength as you move out, back toward the surface of the steel. By lowering or raising the magnets into the system the field created in the steel will be increased or decreased.
If you think that sounds easy, imagine the strength it takes to pull a reasonably powerful magnet from a fridge. Now imagine pulling the super-soldier serum version of said magnet off the fridge? The force required to move the magnets away from the steel can be up to the weight of a small car!
What’s more, as soon as the magnets are moved, the force required can change in both strength and direction due to an additional loop of steel that directs the field away from the beam. So, once in situ, moving the ZEPTO magnets has to be done carefully through the use of a motor, only requiring a few watts of power over a short period of time.
With great power(-efficiency) comes great responsibility
The team who worked on this is hopeful that the ZEPTO magnet will hail real change in accelerator science. They are hoping that it will prove just as effective as an electromagnet over long periods of time. Giving a solution for particle accelerators reducing their power consumption whilst maintaining great performances.
