Abstract This paper presents an analytical description for the growth of the projected emittance (here just referred to the transverse emittance) based on the concept of the slice emittance in an RF photoinjector. In the RF photoinjector, the slice emittance undergoes small changes, but the projected emittance changes significantly even in the drift space after the injector. Carefully adjusting the parameters of the RF photoinjector, which usually means emittance compensation, the projected emittance can be minimized to the value of the slice emittance. The relation between slice emittance and projected emittance is explained in this paper. An emittance function, which shows such a relation, is also introduced. A model about the emittance growth in the RF photoinjector is established, which accords with the particle simulation results by using the code ASTRA. The condition to minimize the emittance is also given by using the emittance function, which means the emittance compensation in the RF photoinjector.
Received: 11 January 2007
Revised: 25 September 2007
Accepted manuscript online:
Altmetric calculates a score based on the online attention an article receives. Each coloured thread in the circle represents a different type of online attention. The number in the centre is the Altmetric score. Social media and mainstream news media are the main sources that calculate the score. Reference managers such as Mendeley are also tracked but do not contribute to the score. Older articles often score higher because they have had more time to get noticed. To account for this, Altmetric has included the context data for other articles of a similar age.
