Two concepts of short-period, pulse helical undulators

Non-magnetic, pulse undulators are proposed for non-free-electron laser (FEL) applications. Both have a cm-sub-cm period and use a GW–sub-GW power level energy sources available within state-of-the-art technology. A two-beam undulator complements two-beam accelerator (TBA) scheme to generate polarized positrons using intense polarized gamma-photons radiated in a square waveguide powered by microwaves extractor-wakefield decelerator. Another concept revisits a bifilar pulse line carrying co-propagating non-sinusoidal wave driven by a high voltage, ns-pulse, commercial generator. It can be used as a short insertion device (ID) for synchrotron radiation facilities. Undulator factor approaching unity is achievable at substantial gap-to-period ratios exceeding 0.4 for both conceptual designs.