The electron devices in which electrons do not collide with other particles or in which the collision probability is very small in the transport process can be theoretically regarded as general vacuum electron devices. General vacuum electron devices include micro-fabricated vacuum nano-electronic devices. which can work in atmosphere. and some solid-state electron devices with nanosc... https://www.bekindtopets.com/mega-sale-Equi-Jec-7-amazing-offer/