Circularly polarized x-ray generation from an ionization induced laser plasma electron accelerator

Abstract

A laser plasma accelerator could provide high-intensity x-ray radiation as the basis for the next generation compact radiation source. However, there is still a lack of tunability for the radiation polarization, especially the circular polarization. Here, we propose a new method for achieving intense circularly polarized x-rays via circularly polarized 20 TW laser pulses driving plasma wakefield acceleration in the regime of ionization injection. When the laser pulse duration is long enough, the ionization injected electrons would not only possess angular momentum, but also be resonant with the laser pulses, resulting in helix structure trajectories in the process of acceleration. In our simulation, we acquired synchrotron radiation with the circularly polarized degree Pc ∼ 0.8, the pulse duration ∼16 fs, the energy spectrum peak ∼1 keV and the brilliance ∼1.8 × 1020 photons s−1 mm−2 mrad−2/0.1%BW. Such an ultra-fast and ultra-brilliant circularly polarized x-ray source has excellent application prospects in the analysis of complex bio-macro-molecule structures and for probing warm dense matter.

Optical control of transverse motion of ionization injected electrons in a laser plasma accelerator

“…However, in the case of the asymmetrical laser spot, these electrons display helical motion, and their oscillation amplitudes are about 3 µm in both the XY and XZ planes. This kind of rotary motion favors the generation of synchrotron radiation from the orbit angular momentum [19,24] .…”

“…In contrast, another method is ionization-induced injection [14][15][16] , which is used in this study. Owing to the different ionization potential levels of high Z atoms [15,[17][18][19] (such as nitrogen), the outer shell electrons can be ionized instantaneously by the rising edge of the laser pulses (98 eV for N +5 requires an intensity of 2×10 16 W/cm 2 ) and pushed away. The inner shell electrons (552 eV for N +6 requires an intensity of~1×10 19 W/cm 2 ) are ionized close to the peak of the laser intensity envelope.…”

Laser polarization control of ionization-injected electron beams and x-ray radiation in laser wakefield accelerators

“…By contrast, in the LP case, the electron orbits with near zero orbital angular momentum (OAM) are more planar, and elongated along the laser polarization axis (compare also with figure 3). In fact, when electrons are ionized by a CP laser pulse, the photo-ionized electrons possess an OAM due to the rotation of the electric field vector [91]. This angular momentum remains conserved during the whole acceleration stage as the electrons continue to maintain their helical orbits.…”

Influence of non‐uniform magnetic field on relativistic q‐Gaussian laser pulses propagating in magnetized plasmas

“…In the recent years with the advent of high-power lasers, theoretical and experimental studies of the interaction of intense laser pulses with plasmas are active areas of research due to their applications in the fields of plasma wakefields, [1][2][3][4][5][6][7][8] Inertial Confinement Fusion (ICF), [9][10][11] fusion harmonics generation, [12,13] X-ray lasers, [14,15] and laser fusion. [16][17][18] In addition, the interaction of intense laser pulse with plasma can lead to a number of nonlinear effects including, self-focusing, [19][20][21][22][23][24][25] self-compression, [26][27][28] Raman and Brillouin scattering instabilities, [29] as well as modulational and filamentational instabilities.…”