Strong nonlinear phenomenon of focussed sound pulse in superfluid {sup 4}He
- Tokyo Inst. of Technology (Japan)
- Olympus Optical Co., Ltd., Tokyo (Japan)
Superfluid {sup 4}He at low temperatures can be regarded as a mechanical vacuum, where only a few phases are excited. In that case coherent acoustic waves propagate without scattering. These waves resemble a laser beam in a true vacuum. There is however a great different between them with moderate sound power density the system goes into a strong nonlinear region in superfluid {sup 4}He, whereas this does not happen in an optical system. Strong nonlinear phenomena have been observed for a focussed sound pulse of 400 MHz in superfluid {sup 4}He at pressures above 17 bars. Structure is observed in the transmitted power of the focused sound waves, and second harmonics are observed. Here results are presented varying the lens-reflector length z around the exact focal point z{sub o}, to see if these phenomena could be due to interference of various phase waves. The details are not yet completely known and more intensive study is required.
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 138555
- Report Number(s):
- CONF-9206305-; ISSN 0022-2291; TRN: 93:003160
- Journal Information:
- Journal of Low Temperature Physics, Vol. 89, Issue 3-4; Conference: Symposium on quantum fluids and solids, University Park, PA (United States), 15-19 Jun 1992; Other Information: PBD: Nov 1992
- Country of Publication:
- United States
- Language:
- English
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