Appendix: - Mathcad Worksheets

Summary

Safe and reliable operation of vacuum tubes requires careful attention to be paid to their integration into the systems in which they are used. Particular attention must be paid to the electric power supplies especially those for high voltages where the stored energy and the risk of voltage breakdown may be high. The principles of operation of electric power converters and pulsed power supplies are described together with the means of protecting the tube under fault conditions. The operation of a tube also depends upon the correct operation of external radio-frequency, cooling and magnetic systems. The issues involved are discussed together with the protection systems and switch-on and switch-off procedures required. Under normal operation the end of life of a tube is determined by failure of emission from the cathode. Premature failure can be caused by failure of the tube vacuum or the focussing system or by mechanical damage. The symptoms of these causes of failure and the precautions required to avoid them are described. The operation of vacuum tubes also involves hazards from electric shock, radio-frequency and X-ray radiation, implosion and the presence of toxic materials. Their operation is safe if correct operating and handling procedures are employed.