15 Nov 2023

Our Changing World – Superconducting magnets and plasma rockets

From Afternoons, 3:35 pm on 15 November 2023

The Paihau – Robinson Research Institute are taking their first foray into space. They are looking to test a brand-new superconducting magnet and flux pump design to see if it can make plasma rockets more efficient. 

A man and a woman stand in front of a large metallic cylinder with various valves in a lab.

Dr Ben Mallett and Betina Pavri at Robinson Research Institute. Photo: Claire Concannon / RNZ

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Actually, the full and correct name is ‘applied-field magneto plasma dynamic thrusters’. These kinds of rockets don’t produce a huge amount of force – for some, the thrust they produce is equal to the weight of a piece of paper on your hand. However, they are extremely efficient. In the frictionless vacuum of space, over time, they can help spacecrafts build up great speeds and travel long distances.  

Plasma is charged gas, and in these kinds of electric space thruster, electromagnets are used to direct the plasma so that it fires out the back and pushes the rocket forward. But the weight and power requirements of current magnets used in these thrusters is a barrier.  

A large metal cylinder embedded in beams with a glowing purple light emanating from its centre.

The radiant glow given off by the plasma of ionized argon gas in the thruster being built at Paihau – Robinson Research Institute. Photo: Jakub Glowacki

Enter Paihau – Robinson, known for their work with high-temperature superconducting magnets. Superconducting materials conduct electrical current with no resistance, so they can create very powerful electro-magnets when a current is passed through them. They do come with baggage though – a cryocooler to keep the magnet at -200oC and a flux pump to send current through the magnet to power it up.  

All of these parts need to be carefully designed and then tested to see if they can withstand the rigours of space.  

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