What Does It Take To Create Large Magnetic Fields?

[Spacescifi]

Magnetic fields come from mass, amd I read somewhere that certain stars have uber magnetic fields that are so strong they would kill before a person's spacecraft ever hit the star.

 

Question: Is the size of a magnetic field dependent on it's mass? And what is the limit of the strength of magnetic field dependent on?

I presume magnetic field strength depends on magnet material strength as well as power avaliable and waste heat management

[Exoscientist]

 

 Yes. Look up “magnetars”.

 On Earth strong magnetic fields can be created for a short period explosively

  Robert Clark

[JoeSchmuckatelli]

Google magnetar, solar magnetism and Earth's magnetic fields... You will find a lot of information 

Edited July 5, 2022 by JoeSchmuckatelli

[Hannu2]

On 7/5/2022 at 3:17 AM, Spacescifi said:

Magnetic fields come from mass, amd I read somewhere that certain stars have uber magnetic fields that are so strong they would kill before a person's spacecraft ever hit the star.

Magnetic fields come from moving electric charges. There are moving conducting material in celestial bodies. Stars have plasma, planets have liquid metals or salts dissolved in liquids (like ammonia or water), neutron stars have some strange superfluid stuff with some protons and electrons (all of them do not form neutrons) etc. Those lethal magnetic fields are around neutron stars and if you really was at those positions magnetic field would probably not be on the first page of your list of lethal conditions.

 

 

On 7/5/2022 at 3:17 AM, Spacescifi said:

Question: Is the size of a magnetic field dependent on it's mass? And what is the limit of the strength of magnetic field dependent on?

Electromagnetic field have energy which can be handled as mass in relativistic equations. However, that mass have not noticeable effects. Gravity is extremely weak interaction compared to electromagnetism.

I dno not know any absolute limit of magnetic field strength. But extremely high field lose its energy in radiation, pair production etc. and probably those fields around magnetar stars are strongest which practically exist.

 

 

On 7/5/2022 at 3:17 AM, Spacescifi said:

I presume magnetic field strength depends on magnet material strength as well as power avaliable and waste heat management

Do you mean now laboratory magnets? Those are limited by properties of superconductors. Superconductors have certain maximum filed strength. Above that Cooper pairs are broken and material lose superconductivity. I think practical limit is around 20 T in continuous use.

There are no resistive losses in superconductors. You have to put in certain energy to create magnetic field but after that you have to only keep superconductors cold. You have to also dump that energy when you want to turn off the magnet. Uncontrolled quenching (loss of superconductivity) may cause damage. You have also to be very careful if you operate near maximum field. For example piece of ferromagnetic material near the magnet may cause local exceed of max field and quenching.

 

[JoeSchmuckatelli]

6 hours ago, Hannu2 said:

For example piece of ferromagnetic material near the magnet may cause local exceed of max field and quenching

Whelp... You've given me MY google search terms for the day! 

[Hannu2]

21 hours ago, JoeSchmuckatelli said:

Whelp... You've given me MY google search terms for the day! 

Sorry, I probably was pretty technical.

Ferromagnetism is that familiar magnetism. Permanent magnets, inductor and electromagnet cores are often made from ferromagnetic materials. Iron is the the most known example. Ferromagnetic material react very strongly to magnetic field around it. Physics behind the phenomenon is awful mess of advanced quantum mechanics. Electron spins, exchange interactions and so on. I never learned it properly because I did not need it with semiconductors. They are fortunately not ferromagnetic.

There is quite often claims that ferromagnetism is somehow badly understood phenomena. It is not true. It is probably because there is no classical analog and it is therefore omitted in popular material and physics courses before master or PhD level in university.

Quenching is a situation in which superconductor cease to be in superconducting state. It is abrupt phase transition and quenched part get immediately significant resistance. Superconducting coils have very large inductance and also large currents. It means very large energy of magnetic field and that energy is released as heat in quenched part. It may damage the wire straight or boil so much liquid helium that pressure bursts vessels or tubes. It may also be dangerous for user if safety measures are omitted.

It may happen due to some disturbance. For example change in magnetic field around experiment. It is not the only danger that iron tool is attracted at high speed. Crash may be followed by a shower of liquid helium.

 

[JoeSchmuckatelli]

1 hour ago, Hannu2 said:

Sorry, I probably was pretty technical.

Ferromagnetism is that familiar magnetism. Permanent magnets, inductor and electromagnet cores are often made from ferromagnetic materials. Iron is the the most known example. Ferromagnetic material react very strongly to magnetic field around it. Physics behind the phenomenon is awful mess of advanced quantum mechanics. Electron spins, exchange interactions and so on. I never learned it properly because I did not need it with semiconductors. They are fortunately not ferromagnetic.

1 hour ago, Hannu2 said:

 

Quenching is a situation in which superconductor cease to be in superconducting state. It is abrupt phase transition and quenched part get immediately significant resistance. Superconducting coils have very large inductance and also large currents. It means very large energy of magnetic field and that energy is released as heat in quenched part. It may damage the wire straight or boil so much liquid helium that pressure bursts vessels or tubes. It may also be dangerous for user if safety measures are omitted.

It may happen due to some disturbance. For example change in magnetic field around experiment. It is not the only danger that iron tool is attracted at high speed. Crash may be followed by a shower of liquid helium.

 

That was one of the most powerful summations one could ask for! 

Thank you! 

I had never heard of quenching in relation to superconductors (the articles of which I usually just skim to see if any major advancement has been made) - but when I do hear about something new I enjoy delving a bit.  Alas, I haven't the maths background to understand the details - but youve given me enough to find publications and perhaps glean the gist. 

... 

I had to laugh out loud when I read, 

1 hour ago, Hannu2 said:

There is quite often claims that ferromagnetism is somehow badly understood phenomena. It is not true. It is probably because there is no classical analog and it is therefore omitted in popular material and physics courses before master or PhD level in university.

...my kids' middle school science books'sections on magnetism had the familiar drawings of field lines and pictures of iron filings and my thoughts at the time was that I hadn't learned much more than that in college.  So reading your explanation struck my funny bone... Because it's true.  Ferromagnetism and electromagnetism are often presented to the liberal arts students as 'here's the basics, and trust us, this is how it works - let's quickly move on to something else you will barely understand'.  (<Subtle hand wave> 'These are not the maths you are looking for')