Speaking of steady-state strong magnetic field, many people may find it strange. But you may have been exposed. For example, magnetic resonance imaging is a typical application of steady-state strong magnetic field. During MRI scanning, you should change into a hospital gown, remove metal ornaments such as jewelry or watches, put on earplugs, enter a dark tubular space, and stay here for 30 minutes to 1 hour. But the steady-state strong magnetic field in the center of the strong magnetic field is much stronger than that in the hospital. Follow me to see ... steady-state use of strong magnetic field: a powerful weapon for scientists, "If you want to do something well, you must sharpen your tools first", and strong magnetic field is a research tool for scientists. Magnets that can provide a strong magnetic field are called high-strength magnets. High-intensity magnets provide researchers with unusually high magnetic fields.

In this extreme environment, wonderful unknown stories are unfolding inside the material, and scientists can explore the hidden secrets of nature. The strong magnetic field center of Chinese Academy of Sciences is busy all day. Is to build a strong magnet that can generate a steady-state strong magnetic field. This kind of magnets can be divided into three categories: water-cooled magnets, superconducting magnets and hybrid magnets. Before we understand these magnets, let's review the basics. As early as junior high school, the teacher told us the scientific truth of electromagnetism. Electric solenoid can produce magnetic field.

There is a magnetic field around every electrified wire. The magnetic effect of this current was discovered by hans christian oersted in a lecture experiment in 18 19. The magnetic field around household wires and appliances is very weak, for example, only a few milligauss at a distance of one meter from the ceiling fan. In order to make magnets with higher magnetic field, we need to further upgrade this method. As shown in the picture above, what happens if we wind a straight line into a circle? All the "small" and independent magnetic fields "combine" with each other to produce a much larger magnetic field.

Besides, what if we wound a wire into a parallel coil with 10 turns? The generated magnetic field is 10 times that of a single circular wire. By the way, the wire coil wound in this way is called solenoid, and its magnetic field strength increases with the increase of the number of electric coils. If an iron plug is placed in the solenoid, the magnetic field can be further strengthened. Increasing the current is also a way to strengthen the magnetic field. In fact, the design of high-strength magnets in the High-intensity Magnetic Field Science Center of Chinese Academy of Sciences is also based on the basic principles of electromagnetism, but we don't use solenoid as a simple magnetizing device.