Compact soft x-ray source using Thomson scattering

Abstract

A compact soft x-ray source using Thomson scattering, enabled by the combination of a picosecond laser and an electron rf gun, was developed aiming at biological studies such as those using an x-ray microscope. The x-ray source included both a photoinjector system and a picosecond laser system with a tabletop size of 2×2m2. An infrared laser beam (λ0=1047nm) was obtained from an all-solid-state mode-locked Nd:YLF laser system and injected into the photocathode of an accelerator system. A 4.2MeV electron beam was generated from a laser-driven photocathode rf gun system. The residual laser beam was amplified up to about 4.2mJ/pulse using a flash-lamp-pumped laser amplifier. Upon collision of the electron beam with the amplified laser beam, 300eV soft x rays were generated by Thomson backscattering. The stable interaction between the two beams was achieved using the same seed laser pulse for irradiating the photocathode and the scattering process with laser photons.

Observation of redshifting and harmonic radiation in inverse Compton scattering

“…An increase of a L results in decreases of both the J z;0 and J x;0 components, so that radiation energy is converted to the higher order harmonics. The frequency redshift due to the electron's longitudinal position is indicated in the exponential term explicitly, exp½ið (6).…”

“…Through the production of subpicosecond x-ray to γ-ray pulses at photon energies extending from the keV to MeV range and beyond, ICS opens up the class of laser synchrotron sources (LSS) [2] that complement conventional high-average-power synchrotron-light facilities, as well as the linac-based x-ray free-electron laser (XFEL). Pulsed ICS could be invaluable for numerous scientific uses, and its actual application for realizing a tunable, narrow-spectrum and polarized high energy photon source has been vigorously examined [2][3][4][5][6][7].…”

Development of a Compact X-ray Source and Super-sensitization of Photo Resists for Soft X-ray Imaging

“…Using a Nd:YLF (1047 nm) laser beam and a 5 MeV class electron beam generated from a photo-cathode RF-gun system, we have already succeeded in generating inverse Compton X-rays [2]. The energies of the generated X-rays are within so-called "water window" region (250 -500 eV) where the X-ray absorption coefficient of water is much less than those of carbon and nitrogen as shown in Figure 2 [4].…”

“…Figure 1 shows the coordinates of the inverse Compton scattering in the laboratory and electron rest frames. When the electron rest mass (m e ), the electron energy (E b ), Lorentz factor  (E b =m e c 2 ), and the incident laser photon energy (E p ) are defined in the laboratory frame, the energy of scattered photons (E s ) is given as (1) where  is the scattered angle in the electron rest frame and  is the crossing angle in the laboratory frame.…”

“…A compact soft X-ray source via inverse Compton scattering using a photo-cathode RF-gun and a picosecond laser system has been developed at Waseda University [1,2]. Inverse Compton scattering is the inverse energy transfer process of general Compton scattering between Figure 1.…”