Feasibility of diffraction radiation for noninvasive beam diagnostics as characterized in a storage ring

Abstract

In recent years, there has been an increasing demand for noninvasive beam size monitoring on particle accelerators. Ideally, these monitors should be cost effective and require little or no maintenance. These monitors should also be suitable for both linear and circular machines. Here, the experimental setup is described in detail, and the results from a diffraction radiation beam size monitor are presented. This monitor has been tested on the Cornell Electron Storage Ring using a 1 mA (1.6 × 10 10 particles per bunch) single bunch electron beam at 2.1 GeV energy. Images of the target surface and the angular distribution of the emitted diffraction radiation were acquired at wavelengths of 400 and 600 nm. These measurements are compared to two analytical models.

Visible light from modulated electron beam moving between twin circular silver nanowires forming plasmonic photonic molecule

“…The other important wavelength value is around 337.7 nm, where e = -Re 1.This is the approximate quasi-static 'textbook' value for the collective resonance on the LSP modes of a single circular metal wire in the free space [14,[16][17][18][19]. It is valid if the losses can be neglected, e = Im 0.…”

“…Today this effect is considered to be a particular case of more broadly defined phenomenon: the radiation that occurs if the charged particles or their beams excite nearby material objects without touching them, in various frequency regions. Such an effect is called diffraction radiation (DR) [5][6][7][8][9][10][11][12][13][14], in order to distinguish it from the transient radiation appearing when a particle crosses a boundary between different materials. Physically, the sources of DR are the surface and polarization currents induced on the scatterers placed in proximity to the beam trajectory.…”

“…Microwave-range DR is already in use as an attractive technique for non-invasive beam diagnostics, i.e. remote sensing of the beam position and velocity [10][11][12][13][14]. Such sensors are usually called beam position monitors (BPM).…”

Noninvasive Micrometer-Scale Particle-Beam Size Measurement Using Optical Diffraction Radiation in the Ultraviolet Wavelength Range

“…In addition, the coplanarity between the slit edges must be kept below a fraction of wavelength (≤λ/10) to guarantee that the radiation produced by the two edges from the same particle sums coherently [22,35]. To allow measurement in the UV range down to 200 nm, the coplanarity must therefore be better than 20 nm.…”

“…To ensure sufficient resolution, the optical instrument is designed to record radiation at different wavelengths, down to the UV range at 250 nm. After preparatory experiments [22], a procedure for the fabrication of a suitable ODR target is established, with several prototypes produced at the École polytechnique fédérale de Lausanne (EPFL). Such a target consists of a series of rectangular micrometer-scale apertures on an optical-grade substrate that, when used after a mask, allow one to reduce significantly the SR background.…”