Session R06: Emerging Technologies for Future Accelerators

Live

Recent advances in high gradient cryogenic Cu structure RF research have opened the door to use of surface electric fields between 250 and 500 MV/m. Such structures can enable a new generation of photoinjectors with brightness an order of magnitude beyond the state-of-the-art. Further, one may accelerate these beams to GeV scale in \textless 10 m. Such an injector, when combined with IFEL bunching techniques can produce multi-kA beams with 50 nm-rad emittance. These beams, when injected into innovative, short-period (1-10 mm) undulators enable ultra-compact X-ray FELs having footprints consistent with university-scale laboratories. We discuss the design and performance of this novel light source, which promises photon production per pulse of a few percent of existing XFELs. In the context of a nascent project on UCLA to develop this instrument, we review implementation issues including collective beam effects, compact X-ray optics systems, and various technical challenges. To illustrate the potential of such a light source to fundamentally change the current paradigm of XFELs with their limited access, we examine applications in biology, chemistry, materials, and atomic physics which may take advantage of this new model of performing XFEL science.   

Live

The high-energy physics (HEP) research in the post-LHC era relies on a next circular collider. The energy of a circular collider is limited by the strength of the bending dipoles, and its luminosity by the strength of the final focus quadrupoles. These considerations explain the continuous interest of the HEP and accelerator communities to stronger superconducting (SC) accelerator magnets. The ultimate field of SC magnets is limited by the upper critical field B$_{\mathrm{c2}}$, critical temperature T$_{\mathrm{c}}$ and critical current density J$_{\mathrm{c}}$ of the superconductor. The maximum field of the Nb-Ti magnets used in present high-energy machines, including the LHC, is limited to \textasciitilde 10 T at 1.9 K. The fields above 10 T are now possible thanks to the recent progress with the Nb$_{\mathrm{3}}$Sn composite wires and the associated magnet technologies. It was shown that Nb$_{\mathrm{3}}$Sn magnets can operate at fields up to \textasciitilde 15 T. To move beyond 15 T requires high-field high-temperature superconductors (HTS), such as BSCCO and REBCO. Operation above 15 T also put additional requirements to magnet design, technologies and performance. Due to the substantially higher HTS cost and lower J$_{\mathrm{c}}$ at low magnetic fields, a hybrid approach is a cost-effective option for the high-field magnets. This presentation describes the status and main results of the practical superconductors and high-field accelerator magnets, and discusses the design concepts, technologies, and performance parameters needed beyond 15 T.   

Live

Over the past two decades, several X-ray free-electron laser (XFEL) facilities have been built that now deliver X-rays of unprecedented intensity and brightness for science. While this represents a monumental achievement, the X-ray longitudinal coherence, stability, and intensity is limited because all present XFELs are single-pass amplifiers that start from noise. One way to improve the longitudinal coherence and ultimate performance is to follow the example of atomic lasers: build an optical cavity. This talk will discuss recent research efforts aimed at developing such an optical cavity for an XFEL. I will begin by describing the basic X-ray components and physics, paying particular attention to the high-quality optical elements needed to recirculate X-rays. Recent work at Argonne and other labs has shown that X-ray components with the performance characteristics required for an XFEL can be built. These advances have led to the recent funding of a collaborative effort between Argonne and SLAC to install a rectangular X-ray cavity at the LCLS-II. I will describe our plans to design and build such a cavity, and then test its performance and FEL gain at the LCLS using two electron bunches.