Ultrafast Time-Integrated Diagnosis of Laser-Heated Deuterium Ions in Dense Plasma via Fusion Neutron Spectra

The ultrafast time-integrated diagnosis of ions plays a vital role in high-energy-density physics research. However, it is extremely challenging to measure in experiment. Here, we demonstrate a reliable approach for investigating the dynamics of deuterium ions in dense plasma. By irradiating a heavy water stream with the hundred Hertz repetitive intense femtosecond laser pulses, the neutrons from the <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"> <mml:mi>D</mml:mi> <mml:msup> <mml:mfenced close=")" open="(" separators=","> <mml:mi>D</mml:mi> <mml:mi>n</mml:mi> </mml:mfenced> <mml:mn>3</mml:mn> </mml:msup> <mml:mi mathvariant="italic">He</mml:mi> </mml:math> reaction can be detected via a single time-of-flight detector to accumulate the spectrum with a fine energy resolution. This spectrum has been utilized to calculate the temperature and angular distribution of deuterium ions transported in plasma. The calculated results are well verified by particle-in-cell simulations of deuterium ions dynamics. Our method paves a new way for diagnosing ions’ picosecond time-integrated dynamics in plasma and holds great potential for understanding the ions’ transport process in high-energy-density matters and studying laser plasma ion acceleration.