1. I. Langmuir, Phys. Rev 33, 954 (1929).
2. V. M. Belkin, M. A. Zav’yalov, A. A. Kamunin, Radiotekh. Elektron. (Moscow) 21, 2646 (1976).
3. M. A. Zav’yalov, Yu. E. Kreindel’, A. A. Novikov, and L. P. Shanturin, Plasma Processes in Technological Electron Guns (Energoatomizdat, Moscow, 1989) [in Russian].
4. P. I. Akimov and A. B. Bogoslovskaya, Prikl. Fiz., No. 4, 90 (2002).
5. W. L. Howes, J. Appl. Phys. 36, 2039 (1965).