How To Trap Particles in a Particle Accelerator

In particle accelerators, beams of particles are focused and fired forward at almost the speed of light. But how are those particles controlled? With the help of two visual demonstrations, Suzie Sheehy explains.

Keeping a handle on particles is key to the huge range of applications particle accelerators have. The machines accelerate beams of particles using electric and magnetic fields. Suzie uses a ‘Paul trap’ to show how rapidly oscillating currents are used to keep particles on track. A ball on the saddle apparatus is kept in the centre by the rising sides. But that only controls the ball in one direction, meaning it can drop off. Magnetic or electric fields are similar, and can only direct particles in one plane at a time. When the kit begins to spin, though, the alternating position of the rising sides means the ball is contained in the center. This has the same effect that quadrupole magnets in an accelerator have, constantly alternating gradients to keep particles in line.

Using a more sophisticated setup, a quadrupole linear Paul trap, pollen grains can be held in place in a beam just as particles in an accelerator would be. Oscillating fields established across rods on opposite corners of the system keep the pollen particles trapped. Without the rapidly changing fields, the particles would just shoot off in one direction; it’s the changes that keep them from escaping in one or the other direction.

These simple analogies show how particle accelerators guide particles into focused beams, to be harnessed for a huge range of applications.

This video is supported by the Science and Technology Facilities Council.

[biggsydaboss]

She does such a good job of explaining things in plain English. She would make.for an excellent science communicator.

[darthluxor]

Nice, clear, to the point. A four year old can understand this explanation. I was having a hard time understanding the magnetic and electrical forces behind in a quadruple, and didn't find a clear explanation until I found Suzie. My department just got three instruments with mass spectrographs detectors on them (ICPMS, GCMS, and LCMS), and I am in a crunch to understand how they work to isolate and move the positive ion. Thanks Suzie!!

[AtlasReburdened]

Another delightful video. Many compliments Suzie.

[xBris]

I just love Suzie. Great presenter, great scientist! Would love to see more of her.

[johnnythreefour]

3:55 It sure was a beautiful demonstration ;)

[erictaylor]

I wish I had seen this BEFORE watching Dr Sheehy's lecture.

[mmarsbarr]

This was cool and a good demonstration, thanks!

[mybluemars]

That is absolutely amazing! Thank you!

[fmaion]

Really nice!
Is it possible to use this same principle to cool things? Because, I understand that temperature is related to particle movement, if you limit its movement (in xyz), your are removing heat. Is it possible?

[rinzej]

Nice video!

But at 1:06 : "you can't focus a beam of particles in both directions with either a static electric OR magnetic field".

With a static electric AND magnetic field you can confine both positive and negative particles .. anyway according my computer simulation. (see SEM fusor)

[codegeeks]

Okay, so is the reason why it is oscillating that it needs to stay in the absolute center? If it didn't need to stay still would just having the north side of a permanent magnet do the job, for say, researching movement of electrons

[preethamkumar]

Earnshaw’s theorem : A charged particle cannot be held in a stable equilibrium by electrostatic forces alone —— Griffiths

[fleXcope]

Does Paul Trap have anything to do with "resonance"?

[piyush__upadhyay]

how to gain power from charged particle to use appliances?

[jjer]

could a modified version of this be used to control the position of idividual particules in 3D space ?

[eXtremeDR]

Is there a limit to how many particles can be trapped?

[alansmithee]

Run into the cafeteria and throw that cup of pollen into the air.

[johnnyb]

This has to be the same technique used for gathering antimatter. My question is why is antimatter so hard to produce? Is it simply the probability per particle to become an antiparticle is so low we cannot gather enough fast enough to make meaningful amounts? By meaningful I mean useful in ways like space travel and propulsion.

[valeriobertoncello]

Who else saw the same demonstration done in London, at the royal institution (there was an exposition) in the beginning of july?

[CelticSaint]

I just use a jam jar to catch them. Oh wait, that's spiders. As you were.