Commonly used Dewar tanks have a capacity of 100-500L. If the amount of liquid helium that needs to be supplemented exceeds 500L, several Dewar tanks are required to supplement it. At this time, do not pull out the siphon from one dewar and insert it directly into the other, lest the relatively overheated siphon enters the dewar to cause the liquid helium to evaporate sharply, and a large amount of helium will be generated instantaneously to break the bursting membrane and cause quenching. If ice is found during helium transportation, immediately close the helium valve and heat it with a heat gun. When the problem is solved, continue to supply helium. If there is a sharp whistling sound in the helium pipe, it means that the liquid helium in the dewar is almost empty. At this time, close the helium valve quickly, pull out the siphon tube from the helium pipe and seal the helium pipe , The one-way valve is reset. What are the other installation items for the MRI inspection coil? The next step is Energizing the magnet .
Energizing the magnet refers to the process in which the superconducting magnetic resonance equipment gradually applies current to the superconducting coil under the control of the magnet power supply to establish a predetermined magnetic field. Once the excitation is successful, the superconducting magnet will provide a strong, highly stable uniform magnetic field without consuming energy. What are the energizing the magnet preparations for the MRI inspection coil?
- Complement the refrigerant. When the superconducting environment was just established, because the temperature of the cryogenic container was still unstable, the refrigerant volatilized too fast, and the liquid helium and liquid nitrogen levels might be lower than 80%, which should be supplemented and re-excited.
- Establish a security system between the magnets. Check the relevant control circuits, especially the emergency quench switch, the magnet chamber oxygen monitor and other components to ensure that these devices are working properly.
- Install magnetic field detection equipment.
- On-site cleaning. Clean the site thoroughly, remove all ferromagnetic objects near the magnet, and prepare special non-magnetic tools.
- Which hazard signs are set on the MRI inspection coil? Hazard warning signs are hung outside the magnet to prevent patients with artificial implants such as pacemakers from entering by mistake.