A Method for Increasing the Multiturn Injection Efficiency in AG Proton Synchrotrons by Means of Skew Quadrupoles

An increase of the injection efficiency due to linear coupling [already known at the Cosmotron in 1953¹)] is shown to work in AG Proton Synchrotrons for Q_H - Q_V = P. The system is in operational use at the CERN Proton Synchrotron Booster (PSB) to reach intensities above 10¹³ ppp. An intensity increase of 20% is achieved at the expense of a slight vertical blow-up, which is however not noticeable for high-intensity beams as their emittance is already increased because of an integer stop-band. In this paper a comprehensive model is presented, which describes the efficiency as a function of several parameters, such as the coupling strength, injection geometry and Q-values. Provided enough vertical acceptance is available, the same scheme may be profitable for other accelerators using betatron stacking for |Q_H - Q_V - P| < 0.1; ε_H >> ε_V.