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Hello,

I am a newbie learner on MRI system. I am fascinated about superconducting magnet in MRI , which using Liquid helium ,
to prevent helium for boiling off, we need to give vacuum chamber as insulating layer. we can see in this picture below





that picture make me really curious. how does one physically made a vacuum chamber. I am not asking how to suck out the air from it.I mean, if you think about it. Vacuum chamber contain nothing in it right, so how does it suspend their inner layer, which contain liquid helium and coil. the inner core cannot just floating right? there gonna be some way to suspend the inner core.

if somebody may say there is metallic foundation inside the vacuum chamber, so that the inner core is suspend, then the temperature will flow by conduction right.?

so there must be non metallic thing inside vacuum chamber to suspend the inner core? is that right?

(02-17-2017 12:16 PM)hansfryko Wrote: [ -> ]Hello,

I am a newbie learner on MRI system. I am fascinated about superconducting magnet in MRI , which using Liquid helium ,
to prevent helium for boiling off, we need to give vacuum chamber as insulating layer. we can see in this picture below


that picture make me really curious. how does one physically made a vacuum chamber. I am not asking how to suck out the air from it.I mean, if you think about it. Vacuum chamber contain nothing in it right, so how does it suspend their inner layer, which contain liquid helium and coil. the inner core cannot just floating right? there gonna be some way to suspend the inner core.

if somebody may say there is metallic foundation inside the vacuum chamber, so that the inner core is suspend, then the temperature will flow by conduction right.?

so there must be non metallic thing inside vacuum chamber to suspend the inner core? is that right?

The vacuum vessel will not be floating in mid air. They will be hung using suspension systems. These suspensions will be made using high strength, low thermal conductivity materials (eg: G10) to minimize heat flow.

Another interesting piece of information is that there will be a thermal shield (or more than one) that is placed in between the vacuum vessel and helium vessel (inner core) which is also suspended mid air (or mid vacuum ) in similar fashion.
you can see one of such designs in this patent

NB: This technology is not just used in MRI but in most large scale 'DEWAR VESSELS' that store cryogens such as liquid helium or Liquid Nitrogen