Laser-produced plasma water-window x-ray source by continuous liquid bismuth jet.

Area of Science:

• Physics
• Materials Science
• Optics

Background:

• X-ray sources are crucial for various scientific and technological applications.
• Developing stable and efficient water-window (WW) x-ray sources remains a challenge.
• Liquid targets offer potential advantages for high-repetition-rate x-ray generation.

Purpose of the Study:

• To demonstrate a continuously operated water-window x-ray source.
• To investigate the performance of a regenerative liquid bismuth jet for x-ray generation.
• To assess the potential of this source for future applications like extreme ultraviolet lithography and biological imaging.

Main Methods:

• Utilized a regenerative liquid bismuth (Bi) jet with a diameter of 35-40 µm injected into a vacuum.
• Operated the source continuously for 120 minutes.
• Characterized the emitted photons per pulse at specific wavelengths (4.1 nm, 4.3 nm, 2.8 nm) and the overall spectral range (2.3-4.4 nm).

Main Results:

• Achieved continuous operation of the water-window x-ray source for 120 minutes.
• Measured photon flux of 3-4.2 × 10^11 photons/sr at 4.1-4.3 nm (n=4-4 transitions) and 1.7 × 10^11 photons/sr at 2.8 nm (n=4-5 transitions).
• Observed a total photon emission of 10^12-10^13 photons/(nm·sr) in the 2.3-4.4 nm range and a power law scaling of spectra with laser intensity (power of 0.4).

Conclusions:

• The regenerative liquid bismuth jet provides a stable and continuous water-window x-ray source.
• This technology shows significant potential for next-generation extreme ultraviolet lithography.
• The source is a viable candidate for advanced x-ray microscopy in biological imaging.