Surface-micromachined magnetic undulator with period length between10  μmand 1 mm for advanced light sources

Abstract

A technological gap exists between the m-scale wiggling periods achieved using electromagnetic waves of high intensity laser pulses and the mm scale of permanent-magnet and superconducting undulators. In the sub-mm range, surface-micromachined soft-magnetic micro-electro-mechanical system inductors with integrated solenoidal coils have already experimentally demonstrated 100 to 500 mT field amplitude across air gaps as large as 15 m. Simulations indicate that magnetic fields as large as 1.5 T across 50 m inductor gaps are feasible. A simple rearranging of the yoke and pole geometry allows for fabrication of 10+ cm long undulator structures with period lengths between 12:5 m and 1 mm. Such undulators find application both in high average power spontaneous emission sources and, if used in combination with ultrahigh-brightness electron beams, could lead to the realization of low energy compact free-electron lasers. Challenges include electron energy broadening due to wakefields and Joule heating in the electromagnet.

Physics of Phase Space Matching for Staging Plasma and Traditional Accelerator Components Using Longitudinally Tailored Plasma Profiles

“…In traditional accelerators, solenoids and quadrupoles are typ-ically combined to guide the transverse motion of the particles between the stages. However, due to ultrahigh focusing gradient in the nonlinear plasma wake (G[MT/m] ≡ F r /ecr ≈ 3.01n p [10 17 cm −3 ]), state of the art quadrupoles (G ∼ 10 3 T/m) [36,37] are not strong enough to confine the transverse motion of the particles between the stages. Here F r is the transverse focusing force in the direction r and n p is the plasma density.…”

Next generation high brightness electron beams from ultrahigh field cryogenic rf photocathode sources

“…The harder x-ray case discussed in this paper proposes use of very short period undulators. One may take this concept a step further and use yet shorter period undulators, to the sub-mm-period scale [125], which may be used for creating x-ray FELs at very low beam energy [126]. This type of free-electron laser demands that very strong focusing [127] and extremely high brightness, low emittance beams be used.…”

Generation X-ray – A coming of age

“…The fourth generation sources are still in their infancy but the possibilities of fifth generation sources based on energy-recovery Linacs, or micro-fabricated undulators (Harrison et al, 2012) and Laser Plasma WakeField Accelerators (Couprie et al, 2013), are already being pursued. Light sources naturally promote the formation of networks across disciplines and borders, and in the age of "big data" are very much symbols of modern globalized science.…”