抄録
A superconducting lens system for ultra high voltage electron microscope has been completed. This is designed to have such construction that it can be replace the standard image forming system of electron microscope.
The magnetic circuit of the lens system is made of Permendur. The maximum axial field strength at the excitation of 40, 000 Amper turns is about 46kG, and the computed focal length for this field distribution is 2.7mm.
The liquid Helium is stored in a reservoir tank which is located above the lens part. The reservoir has the capacity of about 1.5 litres and it is enough to keep the lens in the superconducting condition for about 1hour.
Electron micrographs taken with the superconducting lens operated under the persistent current mode are demonstrating.
