Superconducting for electromagnetic shielding.

[Rstoddart]

Back in college physics, the professors were teaching us that Superconductors would absorb radiation.

Later in my career, I go to discuss Starships with a venerable old physicist. PhD, MD. and he told me that Superconductors could be used to protect a ship from radiation.

 

At worldcon this past weekend (The World Science Fiction Convention) We discussed potential solutions to protection people from radiation. To which I brought up the possibility of Superconductive properties providing shielding.

 

Now I am in doubt, and doing some research, and hit a limit of my knoweldge of physics. And came here to get some input.

 

I found a article that showed research of Superconductors for shielding. and they specified in the abstract that t hey worked well ok in the lower mm length wavelengths. (50-100 GHZ. ) and copper was superior.

 

then I found a article on: https://www.britannica.com/science/superconductivity

that says:

"The energy gap in a superconductor has a direct effect on the absorption of electromagnetic radiation. At low temperatures, at which a negligible fraction of the electrons are thermally excited to states above the gap, the superconductor can absorb energy only in a quantized amount that is at least twice the gap energy (at absolute zero, 2Δ0). In the absorption process, a photon (a quantum of electromagnetic energy) is absorbed, and a Cooper pair is broken; both electrons in the pair become excited. The photon’s energy (E) is related to its frequency (ν) by the Planck relation, E = hν, in which h is Planck’s constant (6.63 × 10−34 joule second). Hence the superconductor can absorb electromagnetic energy only for frequencies at least as large as 2Δ0/h."

 

So Is there a table, or reference for the "energy gap" values for superconductors?

This would tell me what frequencies of electromagnetic (photons) radiation that it will absorb.

 

I am to interpret that these numbers are at absolute zero. Perhaps with 2nd generation superconductors, they might be needing to be calculated at their "sweet Spot" temperature.

 

Do high temperature superconductors (2nd generation) Have this same property?

 

Thank you for your help.

Edited August 25, 2016 by Rstoddart

[Sensei]

Back in college physics, the professors were teaching us that Superconductors would absorb radiation.

Later in my career, I go to discuss Starships with a venerable old physicist. PhD, MD. and he told me that Superconductors could be used to protect a ship from radiation.

Which radiation do you have in mind?

There is plentiful: alpha, beta, gamma, proton, neutron, cosmic rays, and more.

 

If through conductor there is flowing current, there is created magnetic field around it.

Superconductor will have it much stronger (much larger current possible to flow).

As we can see in CRT, Cathode Ray Tube, electrons emitted by electron gun to chamber,

their paths can be bend by electric field (gathered on metal electrode electrons or their absence),

or can be bend by magnetic field (made by electromagnet on demand, polarized in one direction or other).

But that works good for charged particles.

Alpha has +2e charge, beta particles electron has -1e charge, positron +1e charge.

Cosmic rays have typically +1e and -1e (mesons, 2nd and 3rd generations leptons, unstable baryons etc.).

Gamma, neutron, and other neutral particles won't have serious problem entering to object protected by superconductor/conductor which is used to make electromagnet.

 

Superconducting for electromagnetic shielding.

To me shielding means ability to disallow particle to enter to inside of shielded object.

If particle does not interact with shield, does not absorb, does not reflect,

then particle will pass through it to inside no problem...

It will be transparent. Rendering shield useless.

 

See shield made of Gold foil for alpha radiation at 0:35

There is plentiful alpha particles on the left emitted by radioactive isotope,

behind Gold foil on the right, there is much less (but still some are present).

That's good example of shielding, against this particular type of radiation.

Edited August 26, 2016 by Sensei

[Rstoddart]

Thank you for your response.

Cosmic radiation being made up of more exotic particles, was something I had not considered.

I am going to need to consider them. I am not as familiar with their behavior. I was under the impression that they were not stable, and wouldn’t be seen in the wild.

I think the best approach is to categorize particles that make up the radiation in space that astronauts will need to deal with are in 3 categories.

• Mass particles

• Massless Particles.

• Secondary particles. (Those released when they are absorbed or reflected.)

Effective space ship shield, based on the physics we know today, will require multiple types of shielding, to deal with the various types. For example, protecting against the stray rare anti-mater will requires some sort of mass, but is should occur before the shielding for gamma radiation, as matter/antimatter annihilation produces gamma radiation.

Mass particles, such as protons, neutrons, electrons, and their anti-particles. Can be dealt with readily. I have read that Europium is a good absorber of neutrons. Protons are strongly interacting, and I have told it will be absorbed easily, as your lovely video above shows.

This raises the secondary radiation problem again. As hulls seem to be made of aluminum. What is the resulting effect of adding a proton or neutron to the material? For example, adding protons to uranium results in producing plutonium.

Electrons are easily bent with magnetic fields, and absorbed by various metal alloys

Secondary particles represent another problem. While there is currently work on creating magnetic bubbles for space travel. There is going to be secondary currents generated by moving inside them. The field strengths they discuss are extremely high. And this will be difficult to maintain, and the induced forces and currents on the occupants will likely cause problems. As an emergency stopgap measure during solar storms, they would be ok. And I suspect that directional shielding will optimal. However, the northern lights are another example of what is produced when the particles hit the earth’s magnetic field.

However, the only particle I don’t have a good handle on is high energy photons. They make up the gamma, and x-rays that are disruptive. But are not blocked easily. I understand that the hydrogen atoms will block them. And tanks of water are proposed for managing them. This is the mass solution.

I am trying to figure out if a possible solution that would absorb/reflect radiation could be reasonably developed that could be used in a ship hull that does not take a tremendous amount of energy to maintain. And be very reliable.

I was curious to find out if Superconductors would be a good thinner less massive approach to blocking x-ray and gamma rays from passing into a spaceship hull. I had hope to calculate the frequency capacity of various super conductors by getting the elusive “gap energy” for that material. Or if I am misunderstanding the nature of what Gap energy is.

I’d rather use some real effect in my story than a sheet of Mythium. Unobtanium is ok, if it is reasonably likely that it will be developed in the near future.

(a new material is recently developed that make solar sails possible. )

 

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