Multi-Moded Multi-Frequency Fast Single Bunch Beam Diagnostic Instrument

Although beam control is critical to the optimal operation of accelerators, both for the large systems that exists in national and international laboratories and for industrial and medical accelerators, it is compromised by the high costs of diagnostic detectors and the need for information from multiple detectors to generate a complete picture of what is happening to the beam. Moreover, some of the measurements are destructive to the beam or take a long time to interpret results. Ideally one would like to design and build a fast, non-destructive beam monitor that can provide beam intensity, position and size information almost instantaneously and be able to operate fast enough to diagnose individual beam bunches. Making such devices economically enough for widespread use is also required, it is no use to make a “perfect” system if it is unaffordable. We propose to create cavity monitors in which the azimuthal symmetry is perturbed and hence the different polarizations of the dipole and quadrupole modes are shifted in frequency. Adding this additional frequency information to the amplitudes will allow a single cavity to provide at least five pieces of information related to the charge, the horizontal and vertical dipole modes and the two polarizations of the quadrupole modes. This novel solution can provide for a compact device that can non-destructively monitor the beam position, size and eventually emittance at high repetition rates. Moreover, installing multiple monitors in a FODO lattice in a machine such as LCLS-II will allow fast emittance measurements. The proposed beam monitor will be fast, compact, economical and be capable of non-destructive measurement of beam parameters. These qualities will allow for more widespread use in the ~1500 or so medical and industrial linacs manufactured per year leading to better monitoring of output radiation of these systems, especially medical radiation therapy systems where beam monitoring can be critical to operation. Often the manufactures of such systems will forgo meaningful beam diagnostics for cost reasons. The large accelerator laboratories also have need for fast, non-destructive beam diagnostics for better beam tuning as they strive for better quality beams needed for ultimate performance.