Measurement of shock and re-shock Hugoniot data of liquid nitrogen

ABSTRACT

In this work, the equation-of-state data for liquid nitrogen shock compressed to 43 GPa along the principal Hugoniot and reflected-shock data up to 91 GPa were reported. A cryogenic target was used to liquefy the gas that was then further compressed by high-speed impactors. The first- and second-shock states were observed by a high-precision Doppler pin system (DPS). Optical wavefrom of DPS resulted in the first-shock velocity from which other derivative quantities i.e. particle-velocity, specific-volume, internal-energy, and Grüneisen-parameter, were determined. Our results and published equation-of-state data were used to extrapolate the principal Hugoniot. Their comparison showed softening above 27 GPa, attributed to the absorption of thermal energy that dissociates the molecular nitrogen. Our single-shock data provided a good match to available Hugoniot data. The reduced velocity profiles allowed us to detect optical reflectance of the dissociated liquid phase, and the apparent shock-velocity was used to determine the true shock-velocity in dissociation threshold.

KEYWORDS:

• Shock compression
• LN₂
• Hugoniot data
• phase transition
• shock cooling

Acknowledgements

This experimental series was supported by the School of Physical Science and Technology, Southwest Jiaotong University, Chengdu. The authors would like to thank all associates, mechanical assistants, and teachers for their help. The authors acknowledge an anonymous reviewer for his/her constructive comments.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

The reported study was funded by the School of Physical Science and Technology, Southwest Jiaotong University, Chengdu.