High-frequency Electron Beam Research Articles

High-frequency electron beam modulation by a ferroelectric cathode with anomalous plasma resistance

Spectroscopic measurements are reported of the plasma formed inside a cathode having a ferroelectric source incorporated in it. These measurements were performed during the generation of a high-frequency modulated electron beam in a planar diode with the above cathode. It was found that there is a spatially periodic structure in the plasma density, electric field, and electron energy in the plasma in the longitudinal direction from the ferroelectric surface. The plasma density, electric field, and electron energy vary in the range of 5×1013–5×1014 cm−3, 0–1 kV/cm, and 2–30 eV, respectively. Also, it was found that the plasma electron temperature is ∼8 eV in the vicinity of the ferroelectric surface and ∼2 eV in the bulk of the plasma. To explain the obtained experimental data a qualitative model is suggested. The model is based on fast periodic appearance of anomalous plasma resistance due to generation of ion-acoustic instability. The latter is controlled by the ratio between the velocities of the current carrying electrons and the ion sound. Computer simulations show good agreement with the experimentally obtained data.

Fabrication of high-frequency electron beam moiré grating using multi-deposited layer techniques

This paper proposed new ways for producing multi-layer model grids for electron beam moiré method. An electron beam lithography system was set up under scanning electron microscope which was equipped with a beam blanking device and a pattern generator. The two-deposited-metal layers method was used to manufacture electron beam grating for high-temperature use. The results verify that the Zr–Pt-type grating possesses heat resistance up to 1100°C in vacuum. A new type of composite grating with frequencies 100 lines/ mm and 1000 lines/ mm using three deposited layers was produced. A 10 000 lines/ mm two-deposited-metal layers grating was successfully fabricated using electron beam lithography.

High-frequency electron beam modulation in a diode with an active plasma cathode

We have carried out experiments with an active plasma cathode showing the possibility to generate a modulated electron beam with a repetition rate of 2 Hz without the use of a high-frequency power supply. The modulation of the beam current amplitude reaches values ⩾30%. This modulation is found to have a frequency of 325±5 MHz for a discharge capacitor of 1 nF and a duration ⩾1 μs. In addition, the modulated electron beam is accompanied by electromagnetic radiation with the same frequency. We suggest that this high-frequency modulation is caused by electron oscillations within the potential well which is created inside the cathode structure by the positive potential of the plasma.

Ultraviolet HeCd laser pumped by a high-frequency electron beam

An electron beam with a large cross section and with a repetition rate of 3×105 pulses per second in a packet has been obtained for the first time. With this beam a HeCd high-pressure laser has been developed and high-frequency lasing on the Cd ion at a wavelength of 325 nm has also been achieved for the first time.