Multi-keV x-rays are essential for diagnostic applications in inertial confinement fusion and high energy density physics. In this paper, enhancement of the multi-keV x-ray emission is achieved by using a low-coherence green laser to irradiate Ti foil targets at a fractional bandwidth of 0.6%. Compared to the widely used narrowband lasers, the above broadband laser generated 17%–23% more intense He-like alpha x-rays of Ti in the experiments at laser intensities of 4–6 × 1014 W cm-2. The improved laser absorption due to the reduction of stimulated Brillouin scattering introduced by the bandwidth is responsible for the enhancement of x-ray emission. The results suggest a promising application of broadband lasers on x-ray generations and further diagnostics.
This paper demonstrates that using a low-coherence green laser to irradiate titanium foils can generate more intense x-rays in the multi-keV range compared to narrowband lasers. The improved laser absorption due to reduced stimulated Brillouin scattering is the key reason for the enhanced x-ray emission.
Effects of moderate bandwidth on laser absorption and stimulated Raman sidescattering