The minimum heat transfer area of the tube for subcooling and the optimal length range of the by-pass capillary tube were determined.

The former determines the frequency range which should be revised by the hot tracking circuit, while the later is the final frequency error of the local oscillator.

Result of cross section analysis showed that the second phase reduced within a range of several tens microns, and the depth of heat affected zone (HAZ) increased with the increment of pulses.