Secondary electron emission from barium oxide

The effect of temperature on the secondary emission of barium oxide is found to be small between room temperature and 600° C. With evaporated layers, the d.c. value of the secondary emission coefficient at a bombarding energy of 240 V falls from near 3 at 10 -6 cm to about 2 at 10 -4 cm. The pulsed value is about twice as large as the d.c. for the thinner films. For sprayed coatings the coefficient is near 2, and is the same for d.c. as for pulsed. During operation there are rather complex short time effects, but over a long period the coefficient falls, and decomposition of the oxide occurs.