Spectroscopic diagnostics of hydrodynamic luminescence

Abstract Hydrodynamic luminescence occurs when a liquid is flowing through a narrow dielectric channel. The liquid electrifies due to friction from the channel walls; plasma that appears in the channel is the source of light emission. This work studies the spectrum of plasma glow emitted in flow of water through a narrow channel (1 mm in diameter) under pressure of ~100 atm. The spectrum of luminescence contains bands of hydroxyl and nitrogen with addition of lines of hydrogen and oxygen. The water was saturated with argon to achieve more detailed diagnostics results. The results of spectroscopic research of hydrodynamic luminescence of water correlates with previously obtained data for I-40A oil: the vibrational temperature of nitrogen is 4500 K and rotational temperature is 300 K. The estimation of electron temperature shows the result of ~10 4 К. Thus, the conducted experiments confirm the electric nature of excitation of hydrodynamic luminescence. The hydroxyl spectrum shows significant non-equilibrium previously evident in many works dedicated to research of electric discharge in water steam.