Recirculating beam-breakup thresholds for polarized higher-order modes with optical coupling

Recirculating beam-breakup thresholds for polarized higher-order modes with optical coupling

Here we will derive the general theory of the beam-breakup (BBU) instability in recirculating linear accelerators with coupled beam optics and with polarized higher-order dipole modes. The bunches do not have to be at the same radio-frequency phase during each recirculation turn. This is important for the description of energy recovery linacs (ERLs) where beam currents become very large and cou...

Polarized higher-order subtyping

Higher Order Sliding Modes

One of the most important control problems is control under heavy uncertainty conditions. While there are a number of sophisticated methods like adaptation based on identi cation and observation, or absolute stability methods, the most obvious way to withstand the uncertainty is to keep some constraints by "brutal force". Indeed any strictly kept equality removes one "uncertainty dimension". Th...

Selective launching of higher-order modes into an optical fiber with an optical phase shifter.

We demonstrate a simple, effective technique for launching higher-order modes into a double-mode optical fiber by using an optical phase shifter at the input end. The suppression of the lowest-order mode was measured (but not limited) to be 27 dB.

Effects of Higher Order Modes

The surface currents on a two-wire transmission line induced by incident field excitations are investigated using the spectral concept. A simple solution is obtained for plane wave excitation. A solution for voltage source excitation, in which the induced current may be given, at least approximately, by means of the so-called leaky-wave concept, is considered. The influence of the electrical di...