Experimental Demonstration of a Tunable Microwave Undulator

Abstract

Static magnetic undulators used by x-ray light sources are fundamentally too limited to achieve shorter undulator periods and dynamic control. To overcome these limitations, we report experimental demonstration of a novel short-period microwave undulator, essentially a Thomson scattering device, that has yielded tunable spontaneous emission and seeded coherent radiation. Its equivalent undulator period (λ u) is 13.9 mm while it has achieved an equivalent magnetic field of 0.65 T. For future-generation light sources, this device promises a shorter undulator period, a large aperture, and fast dynamic control.

Plasma Undulator Based on Laser Excitation of Wakefields in a Plasma Channel

“…Undulators with periods less than or on the order of a millimeter, often referred to as micro-undulators, are, therefore, of great interest. Several micro-undulator ideas have been proposed including electro-static undulators [3,4], crystalline undulators [5], RF-based [6], laser-plasma-based [7][8][9], and optical undulators [10][11][12][13][14][15][16][17]. In this Letter we propose a micro-undulator based on controlling the transverse forces experienced by an electron beam inside a laserexcited plasma channel.…”

“…(The equation of motion in the transverse direction orthogonal to the laser beam centroid motion is d 2 y/dz 2 + k 2 β y = 0.) The transverse momentum of the electron is (6) where k u = 1/Z R , ψ β is a phase determined by the electron injection relative to the laser beam centroid oscillation,…”

Flexible x-ray source with tunable polarization and orbital angular momentum from Hermite-Gaussian laser modes driven plasma channel wakefield

“…It has recently been experimentally demonstrated that electron optics can, in principle, also be replaced by plasma technology [6][7][8], leaving the undulator as the only major factor defining the size of the facility. Several ideas for undulators with periods on the order of millimeter or below (often referred to as microundulators) have been proposed, including electrostatic [9,10], crystalline [11][12][13], microwave [14], plasma [15], nano-wire [16] and laserbased [17][18][19][20][21][22][23][24][25].…”

Cyclotron Auto-Resonance Accelerator for environmental applications

“…1(b), principally to avoid the size and complexity of the resonant ring, but also to provide flexibility in operating conditions for different levels of beam loading. The standing-wave cavity designs can offer comparable RF-to-beam efficiencies, since a standing wave is the superposition of two counter-propagating travelling waves; wall losses are similar when taking into account the extra length of the resonant ring; and high cavity end-wall losses can be mitigated [10].…”