An electron emitter has an emitter section having a plate shape, a cathode electrode formed on a front surface of the emitter section, and an anode electrode formed on a back surface of the emitter section. A drive voltage from a pulse generation source is applied between the cathode electrode and the anode electrode through a resistor. The anode electrode is connected to GND (ground) through another resistor. A collector electrode is provided above the cathode electrode, and the collector electrode is coated with a fluorescent layer. A bias voltage is applied to the collector electrode through another resistor.