Beam Dynamics in a Hybrid Standing Wave‐Traveling Wave Photoinjector

We discuss the dynamics of a photoinjector beam in a hybrid traveling wave‐standing wave photoinjector. With the field profile deduced from electromagnetic simulations, it is seen that the acceleration program induces strong velocity bunching. The beam dynamics in this scenario are explored using UCLA PARMELA. With a solenoid field overlaid on the TW section one may control emittance oscillations during bunching and acceleration. It is seen that the S‐band device currently under development at UCLA may produce a 1 nC, 21 MeV, 100 micron rms pulse length beam, with emittance of 3 mm‐mrad. Applications of this beam for creating coherent radiation are discussed.