Satoru Nakamura

Drift Velocity of Hot Electrons in Liquid Ar, Kr, and Xe

The drift velocity of hot electrons in liquid Ar, Kr, and Xe near their triple points is studied using a Cohen-Lekner equation in which an inelasic depolarized electron scattering process is newly considered. The saturation of the drift velocity at the high field strength is appropriately explained. The magnitude and onset energy of the effective inelastic cross-section are compared with the experimental data of Raman spectra.

Effective momentum transfer cross section for excess electrons in liquid argon

The momentum-transfer cross section of excess electrons 〈Q〉 in liquid Ar (estimated on the assumption that the characteristic energy 3eD/2μ is equal to the mean agitation energy \ge) is compared with the original momentum-transfer cross section Q1 used for the calculation of D and μ. Differences between 〈Q〉 and Q1 are discussed and comparisons made between 3eD/2μ and \gE.

Monte Carlo simulation of electron transport behavior in liquid argon

Electron transport behaviour in liquid argon is studied using a Monte Carlo method in which the differential cross section defined by Van Hove (1954) for the interaction of an electron with liquid atoms was considered instead of two mean free paths, Lambda /sub 1/ and Lambda /sub 0/ of Cohen and Lekner (1967). The drift velocity and the mean energy of electrons for the field strengths between 10/sup 3/ and 10/sup 4/ V/cm were in good agreement with those obtained by using the Cohen-Lekner equation. The ratio of the injected electrons from a cathode into the liquid to those into vacuum agreed reasonably well with experimental values. >

Excess electrons in N2/Ar liquid mixtures

Abstract Fast and slow electronic current signals in N 2 /Ar liquid mixtures were observed. From the fast signal, the drift velocity and life-time of delocalized electrons in the liquid with N 2 mol fractions x ( = N 2 /(N 2 +Ar)) from 5 to 20% were obtained for field strengths E between 5 and 45 kV/cm. It was shown that the high-field drift velocity increased with increasing x up to 5 mol% and decreased with x above 5 mol%. The life-time increased with increasing E and with decreasing x .

Fast and slow electrons in liquid argon and nitrogen mixtures

Fast and slow electron current signals in N/sub 2//Ar liquid mixtures have been observed. From the fast signal, the drift velocity and lifetime of delocalized electrons in the liquid with N/sub 2/ mol fractions X (= N/sub 2//(N/sub 2/ + Ar)) ranging from 5 to 20 mol% were obtained for field strengths E between 5 and 45 kV/cm. The electron mobility for X = 15 mol% is estimated to be /spl sim/20 cm/sup 2//Vs. The slow signal has shown that the mobility in X = 10 mol% liquid is /spl sim/10/sup -3/ cm/sup 2//Vs, which is the same order of magnitude as that (/spl sim/2.5 /spl times/ 10/sup -3/cm/sup 2//Vs) in liquid N/sub 2/. Characteristics of the localized electrons are discussed.

Photo-electric current in cryogenic liquid mixtures

Mixtures of liquid nitrogen (LN2)/liquid methane (LCH4), LCH4/liquid argon (LAr), and LAr/LN2 with various mixing ratios were produced by cooling down the mixed gases directly in a measurement cell. The liquid temperature with a vapor pressure of 1 bar varied monotonically between the boiling point of every two liquids among LN2, LAr, and LCH4. The ratio of the photoelectric current in the liquids, J/sub L/, to the current in vacuum, J/sub V/, was between those in two component liquids in a wide range of the electric field, E. From J/sub L//J/sub V/ vs. E curves, the electron mobility in the liquid mixtures was estimated.<<ETX>>