Topic number 10

Abstract. Liquid Helium (LHe) at 4.2K was excited using a corona discharge for negative high voltages. The current of corona 100nA was measured which is result of low mobility of electrons in LHe. The pressure increasing up to 10 MPa resulted in weak decreasing of the mobility. Electrons are localized in micro-cavities in LHe. Then experiments were carried out with temperature increasing over the critical temperature 5.2K. The sharp increasing of the corona current was observed at temperatures 7K and 10K under pressures in the range 0.2-0.4 MPa. Current-voltage characteristics were measured and analyzed. The analysis showed the electron mobility increasing by 3 orders of magnitude in these conditions. The transition from localized state of electrons to free electrons state occurs in the supercritical gas in a narrow range of pressures and is explained by quantum-mechanics property of electrons