Penning Trap questions -- capacity, manufacturers, leakiness....

[Funestis]

Does anyone know what the maximum capacity of a Penning Trap is or what this would depend on? Whether the capacity is measured in particles, mass, etc? I would presume that max capacity would depend on field strength of the trap, but if anyone could confirm this I'd be grateful.

A follow-up question - does anybody know of Penning trap manufacturers? It seems like the ones that are in use are 'homemade' so to speak, if there is some company out there that makes these devices I've been unable to find it.

Final question - do Penning traps 'leak'? Maybe a better way to ask this is how stable are they? Do they confine 100% of particles the entire time they are running, or do particles escape? If so, any idea what that escape rate may be?

Thanks everyone for your input, I appreciate the help.

 

[DrClaude]

I am not an experimentalist, so others may be able to give better answers (@mfb ?).

Does anyone know what the maximum capacity of a Penning Trap is or what this would depend on? Whether the capacity is measured in particles, mass, etc? I would presume that max capacity would depend on field strength of the trap, but if anyone could confirm this I'd be grateful.

There is a limit to the ion number density, given by
$$
n_\mathrm{lim} = \frac{B^2}{2 \mu_0 M c^2}
$$
[Werth et al., Charged Particle Traps II - Applications (Springer, Berlin, 2009)]

A follow-up question - does anybody know of Penning trap manufacturers? It seems like the ones that are in use are 'homemade' so to speak, if there is some company out there that makes these devices I've been unable to find it.

As for most research devices, they are mostly homemade. You may be able to find a company to custom build one for you (depends on your budget...).

Final question - do Penning traps 'leak'? Maybe a better way to ask this is how stable are they? Do they confine 100% of particles the entire time they are running, or do particles escape? If so, any idea what that escape rate may be?

Nothing lasts forever, but I have hear of single electrons being trapped for insanely long times (years). I guess that the lifetime of the trap will be related to different real-world parameters, such as the quality of the vacuum.

 

[mfb]

I have never worked with Penning traps (opposite end of the energy spectrum).

BASE stored antiprotons for more than a year, and electrons have been stored for at least several months as well. As BASE didn't see any loss within that year, they could probably store them for a century if there would be a point in that.
Technically particles can escape at every non-zero temperature, but with a good vacuum and once the system is cooled that can be made extremely unlikely.

The Penning traps used in these fundamental science experiments are custom-made. Not necessarily "at home", but nothing you simply order from a catalog.

 

[Rinze Joustra]

Interesting questions.

I cannot answer them very well. But I've made a simulation program of a kind of modified Penning trap. In the simulation it´s possible to confine both electrons and deuterium ions, up to speeds of 3E6 m/s (during the short simulation time lapse).

If you confine only negative electrons, they will repel each other because of the coulomb forces between them. But if at the same time also positive deuterium ions are present, perhaps the negative charges of the electrons and the positive charges of the deuterium ions compensate and the particles will not or less repel each other.

The problem is that it´s only possible to simulate a couple of hundreds of particles, because of lack of computer power.

Now I tried out the following: simulating the movement of particles with 1E10 times the mass and charge of an electron, and also particles with 1E10 times the mass and charge of a deuterium ion. Quite a rough model I suppose, but I was just curious to see what would happen in the simulation.

Best regards

 

[Funestis]

Thank you all for your help.

DrClaude, mfb - I had a strong suspicion most Penning traps in use were of the 'homemade' flavor, but thanks for confirming. The ion number density formula posted was helpful as well as the link, thank you both!