Promising results in tube performance and life were experienced with polyoptically sealed tubes made previously under another contract. The tube type used for study under this contract is a "reliable" type 7190 miniature hydrogen thyratron with hard glass envelope. A number of various polishing and sealing techniques have been under investigation and comparison. An attempt has been made to minimize the work time required to obtain reproducibly good polyoptically polished button stems and bulbs. Significant gains have been made in this area. Secondly, various means of sealing methods have been attempted;they are:n1. The hot ring (900 C to 950 C) localized heating technique, both with the tube envelope at room temperature and also with the tube at 450°C in a baking oven.n2. The intermediate material technique, which includes glass solder (frits), enamels, cements, and metals (gold and silver).n3. True polyoptic sealing;in which a near perfect fit of button to bulb permits a seal to be made by intermolecular migration. This is done at a baking temperature of 450 - 525°C.
展开▼
