Complex sentence: These can be advantageous since a magnetic field itself cannot melt and the plasma can be at millions of degrees kelvin, but there are often thermal problems in the coils, particularly if superconducting coils are used to form the throat and expansion fields.
Split into simpler sentences: These can be advantageous since a magnetic field itself cannot melt and the plasma can be at millions of degrees kelvin. But there are often thermal problems in the coils, particularly if superconducting coils are used to form the throat and expansion fields.