Radiation of difference-frequency sound generated by nonlinear interaction in a silicone rubber cylinder

1976 ◽  
Vol 59 (5) ◽  
pp. 1077 ◽  
Author(s):  
J. D. Ryder
Keyword(s):  
Silicone Rubber ◽  
Nonlinear Interaction ◽  
Difference Frequency ◽  
Frequency Sound

scholarly journals Interaction of high power laser beam with magnetized plasma and THz generation

2010 ◽  
Vol 28 (4) ◽  
pp. 531-537 ◽  
Author(s):  
R.P. Sharma ◽  
A. Monika ◽  
P. Sharma ◽  
P. Chauhan ◽  
A. Ji
Keyword(s):  
Magnetic Field ◽  
Laser Beam ◽  
High Power ◽  
Nonlinear Interaction ◽  
Difference Frequency ◽  
Thz Radiation ◽  
High Power Laser ◽  
Power Laser ◽  
Circularly Polarized ◽  
Paraxial Ray

AbstractThis paper presents an investigation of the excitation of a Tera hertz (THz) radiation by nonlinear interaction of a circularly polarized high power laser beam and density ripple in collisionless magneto plasma. The ponderomotive force due to the nonlinear interaction between the laser and density ripple generates a nonlinear current at a difference frequency. If the appropriate phase matching conditions are satisfied and the frequency of the ripple is appropriate, then this difference frequency can be brought in the THz range. Filamentation (self focusing) of a circularly polarized beam propagating along the direction of ambient magnetic field in plasma is first investigated within paraxial ray approximation. The beam gets focused when the initial power of the laser beam is greater than its critical power. Resulting localized beam couples with the pre-existing density ripple to produce a nonlinear current driving the THz radiation. Analytical expressions for the beam width of the laser beam, electric vector of the THz wave have been obtained. By changing the strength of the magnetic field, one can enhance or suppress the THz emission. For typical laser beam and plasma parameters with the incident laser power flux = 1014 W/cm2, laser beam radius (r0) = 40 µm, laser frequency (ω0) = 1014 rad/s and plasma density (n0) = 3 × 1018 cm−3, normalized ripple density amplitude (μ) = 0.3, the produced THz emission can be at the level of Giga watt in power.

Compressed parametric difference frequency sound with chirp signal

2013 ◽  
Author(s):  
Hideyuki Nomura ◽  
Hideo Adachi ◽  
Tomoo Kamakura ◽  
Gregory Clement
Keyword(s):  
Difference Frequency ◽  
Chirp Signal ◽  
Frequency Sound

Compressed parametric difference frequency sound with chirp signal

2013 ◽  
Vol 133 (5) ◽  
pp. 3556-3556
Author(s):  
Hideyuki Nomura ◽  
Hideo Adachi ◽  
Tomoo Kamakura ◽  
Gregory T. Clement
Keyword(s):  
Difference Frequency ◽  
Chirp Signal ◽  
Frequency Sound

Linear and nonlinear mechanisms of sound radiation by instability waves in subsonic jets

2010 ◽  
Vol 658 ◽  
pp. 509-538 ◽  
Author(s):  
VICTORIA SUPONITSKY ◽  
NEIL D. SANDHAM ◽  
CHRISTOPHER L. MORFEY
Keyword(s):  
Nonlinear Interaction ◽  
Stokes Equations ◽  
Low Frequency ◽  
Current Approach ◽  
Frequency Noise ◽  
Instability Waves ◽  
Frequency Sound ◽  
Highly Nonlinear ◽  
Linear And Nonlinear ◽  
Low Frequency Waves

Linear and nonlinear mechanisms of sound generation in subsonic jets are investigated by numerical simulations of the compressible Navier–Stokes equations. The main goal is to demonstrate that low-frequency waves resulting from nonlinear interaction between primary, highly amplified, instability waves can be efficient sound radiators in subsonic jets. The current approach allows linear, weakly nonlinear and highly nonlinear mechanisms to be distinguished. It is demonstrated that low-frequency waves resulting from nonlinear interaction are more efficient in radiating sound when compared to linear instability waves radiating directly at the same frequencies. The results show that low-frequency sound radiated predominantly in the downstream direction and characterized by a broadband spectral peak near St = 0.2 can be observed in the simulations and described in terms of the nonlinear interaction model. It is also shown that coherent low-frequency sound radiated at higher angles to the jet axis (θ = 60°–707°) is likely to come from the interaction between two helical modes with azimuthal wavenumbers n = ±1. High-frequency noise in both downstream and side-line directions seems to originate from the breakdown of the jet into smaller structures.

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