The viscosity and acoustic impedance of liquid helium-3

1965 ◽  
Vol 289 (1416) ◽  
pp. 34-45 ◽  
Keyword(s):  
Acoustic Impedance ◽  
Low Temperatures ◽  
Fermi Liquid ◽  
Relaxation Times ◽  
Thermal Relaxation ◽  
Sound Waves ◽  
Zero Sound ◽  
Saturated Vapour Pressure ◽  
Saturated Vapour ◽  
Thermal Relaxation Times

Previous experiments have shown that at low temperatures the acoustic impedance of liquid 3 He under the saturated vapour pressure rises by about 10% below about 0.092 °K. This rise is predicted by Landau’s theory of a Fermi liquid. It comes about because, at sufficiently low temperatures, sound waves in liquid 3 He are propagated as a new mode, the so-called zero sound. The present experiments study the dependence on pressure of the temperature and magnitude of the transition in the impedance. The transition temperature is shifted from 0.092 to about 0.07 °K on subjecting the liquid to a pressure of 12.5 atm, and the magnitude of the change considerably reduced. To interpret these results, measurements have also been made of the viscosity as a function of pressure. (These give information about the thermal relaxation times in the liquid.) All the results are in accord with the theory of zero sound in a Fermi liquid.

The acoustic impedance of liquid helium-3

1965 ◽  
Vol 284 (1396) ◽  
pp. 125-136 ◽  
Keyword(s):  
Acoustic Impedance ◽  
Fermi Liquid ◽  
Quartz Crystal ◽  
Zero Sound ◽  
Saturated Vapour Pressure ◽  
Saturated Vapour ◽  
A Value ◽  
Reflexion Coefficient ◽  
Helium 3 ◽  
Good Agreement

Measurements have been made of the acoustic impedance ( Z ) of liquid 3 He under its saturated vapour pressure in the temperature range 0·035 to 0·6°K. A 1000 Mc/s sound wave is propagated along the axis of an X -cut quartz crystal, and undergoes many reflexions from each end of the crystal. Values are obtained for the reflexion coefficient at an interface between quartz and liquid 3 He by comparing the rate at which the signal decays in the crystal, with and without liquid 3 He present on the ends. These values then lead directly to the acoustic impedance ( Z ) of the liquid. Usually, Z / ρ (where ρ is the density) should be equal to the velocity of sound, and above 0·1°K this is found to be so. However, at about 0·1°K the value of Z / ρ increases abruptly, and at lower temperatures has a value about 10% greater. This result is in good agreement with Landau’s theory of a Fermi liquid, which relates the change in impedance with the propagation of a new mode of sound, the so-called 'zero-sound’.

Analysis of Deep Levels in GaAs Detector Diodes Using Impedance Spectroscopy

1993 ◽  
Vol 302 ◽  
Author(s):  
C Eiche ◽  
M Fiederle ◽  
J Weese ◽  
D Maier ◽  
D Ebling ◽  
...  
Keyword(s):  
Cross Section ◽  
Regularization Method ◽  
Capture Cross Section ◽  
Relaxation Times ◽  
Thermal Relaxation ◽  
Simulated Data ◽  
Deep Levels ◽  
Admittance Spectroscopy ◽  
Thermal Relaxation Times ◽  
Level 2

ABSTRACTImpedance or admittance spectroscopy has been shown to be a very convenient tool for the investigation of deep levels in semiconductor junctions. At constant temperature a frequency sweep is performed. After that the impedance signal is analysed by a regularization method based on Tikhonov regularization in order to obtain the thermal relaxation times of the deep levels present in the junction. The high resolution of the regularization method in comparison to conventional techniques is demonstrated using simulated data. The temperature dependence of the thermal relaxation times provides information about the properties of the deep levels such as activation energy or capture cross section. Two donor levels with activation energies dE1 =0.58 eV and dE2 =0.68 eV are observed in our detector diodes. It can be shown that the concentration of level 2 is increased after irradiation.

A nuclear inductor for measurements of thermal relaxation times in liquids

1954 ◽  
Vol 12 (4) ◽  
pp. 519-525 ◽  
Author(s):  
G. Chiarotti ◽  
G. Cristiani ◽  
L. Giulotto ◽  
G. Lanzi
Keyword(s):  
Relaxation Times ◽  
Thermal Relaxation ◽  
Thermal Relaxation Times

Analysis of the Thermal Response in Micromachine under the Thermal Shock

2011 ◽  
Vol 464 ◽  
pp. 583-587
Author(s):  
Ying Ze Wang ◽  
Xin Nan Song
Keyword(s):  
Heat Conduction ◽  
Relaxation Times ◽  
Boundary Surface ◽  
Thermal Relaxation ◽  
Thermal Response ◽  
Heat Propagation ◽  
Hyperbolic Heat Conduction ◽  
Thermal Relaxation Times ◽  
Fourier Heat Conduction ◽  
Sudden Temperature Change

The thermal response for given micromachine with the boundary surface exposed to sudden temperature change is studied by deriving an analytical solution of the hyperbolic heat conduction equation. Using the obtained analytical expression, the temperature profiles at the outer surface and interior of the micro beam are evaluated for various thermal relaxation times. The behaviors of hyperbolic heat propagation in micro beam are analyzed and possible anomalies are discussed by comparing the thermal behaviors of Fourier heat conduction.

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