Evaluation of TWT (Traveling Wave Tube) Cathode Impregnant Manufacturing Procedures

摘要

Impregnant manufacturing procedures were evaluated as part of a program to develop guidelines for producing reliable dispenser cathodes. Such procedures must be controlled in order to eliminate variations in impregnant composition that can give rise to unpredictable cathode performance. Experiments revealed that variations in impregnant composition result primarily from contamination by moisture, incomplete mixing, and incomplete reaction. Procedures developed to overcome these problems are discussed. The following recommendations are made: (1) Alumina must be dried prior to weighing to avoid inaccurate formulation due to moisture. (2) Multiple dry and wet mixing steps are nedded to thoroughly homogenize the starting materials. (3) Calcination temperatures of 1300 + or - 60 C are required to form thoroughly reacted barium calcium aluminates. (4) Thermogravimetry is useful for testing impregnants and starting materials for moisture contamination. Keywords include: Dispenser cathode, Manufacturing, Impregnant, Barium, Calcium, Aluminate, Weighing, Mixing, Calcination, Thermogravimetry, and Carbonate.