Masao Furukawa

Development of Stirling Cryocooler for Use In Space

A cryocooler is designed for the second Bread Board Model (BBM2). This cryocooler is designed to overcome piston stroke shortage in the original Bread Board Model. The new cryocooler increases linear motor force and reduces flow resistance in the connected parts in the compression space. Magnetic bearings are installed to reduce bearing damping forces, in place of ball bearings in the BBM1. The magnetic bearings arc controlled by conventional PID. The 70-K cooling power is 5.2 W, which exceeds the 5 W target. Actual cooldown time is less than the 10 -minutes specification. Influences of suitable phase shift and piston amplitude on cooling power are described for the BBM2. The BBM2 cryocooler is tested for durability.

A new direct proof of the expansion of a Coulomb‐distorted plane wave in Coulomb‐distorted spherical waves

By employing specific properties of confluent hypergeometric functions, it has been directly proved that a Coulomb‐distorted plane wave is expressible in superposition of Coulomb‐distorted spherical waves.