Electron Gun Market Size and Forecasts (2021 - 2031), Global and Regional Share, Trends, and Growth Opportunity Analysis Report Coverage: By Type (4.5V, 6.3V, 6.7V); Application (Cathode Ray Tubes, Welding, Metal Coating, 3D Metal Printers, Metal Powder Production, Vacuum Furnaces, Others) , and Geography (North America, Europe, Asia Pacific, and South and Central America)