6. Conclusion

The use of vacuum as an insulator, particularly to withstand very high voltages, comes up against the limits of solid matter – the electrodes between which the voltage is applied. Considerable progress has been made over the last century in understanding the elementary mechanisms leading to electronic/ionic conduction in a vacuum. Firstly, under the effect of the strong electric field created between the electrodes, the cathode emits electrons (by tunneling or thermionic effect, or a combination of these phenomena).

Experimentally, we have found that despite this emission, it is possible to maintain a low current without arcing, known as the dark current. However, this current severely limits the maximum values of the high voltage applied.

Various models have been used to describe the dependence of breakdown threshold voltages on inter-electrode...