= Electron gun
An <electron gun> creates, accelerates and shapes a directed <electron> beam. A source such as a heated <cathode> supplies <electrons>, an applied <electric potential difference> accelerates them toward an <anode>, and electrodes control the emitted current and beam geometry.
For an <electron> accelerated from rest through potential difference $V$, the ideal gained <kinetic energy> is $eV$, with the voltage sign chosen to accelerate it. Focusing optics then control beam position and convergence. Source size, <energy> spread and <space charge> affect the useful beam; increasing accelerating voltage alone does not guarantee a smaller probe or higher image resolution.
Back to article page
