Acoustic traveling wave tube system and method for forming and propagating acoustic waves
The present invention is an acoustic traveling wave tube system for propagating a directional acoustic wave comprising an acoustic traveling wave tube having a cylindrical shape with a load on one end of the tube, a plurality of excitation rings positioned around a circumference of the tube and spaced at predetermined intervals along a length of the tube and a microprocessor having a database containing a plurality of waveforms representative of acoustic signals. The microprocessor energizes one of the plurality of excitation rings to form an acoustic wave, sequentially energizes one or more of the remaining excitation rings along the length of the tube to amplify the acoustic wave as the acoustic wave travels along the length of the tube, and propagates the acoustic wave from an end of the tube opposite the load as a shaped directional acoustic wave.
1. An acoustic traveling wave tube system for propagating a directional acoustic wave, the system comprising:
an acoustic traveling wave tube having a cylindrical shape with a load on one end of the tube;
a plurality of excitation rings positioned around a circumference of the tube and spaced at predetermined intervals along a length of the tube;
a power amplifier;
an acoustic signal equalizer;
a communications link; and
a microprocessor having a database containing a plurality of waveforms representative of acoustic signals,
wherein the microprocessor energizes one of the plurality of excitation rings to form an acoustic wave, sequentially energizes one or more of the remaining excitation rings along the length of the tube to amplify the acoustic wave as the acoustic wave travels along the length of the tube, and propagates the acoustic wave from an end of the tube opposite the load as a shaped directional acoustic wave.
2. The acoustic traveling wave tube system of claim 1 , wherein the acoustic traveling wave tube is formed of a lightweight rigid material selected from the group consisting of thermoplastics, thermoplastic laminates, structural composite materials, metals, ceramics, glass, wood and graphine.
3. The acoustic traveling wave tube system of claim 1 , wherein the acoustic traveling wave tube is formed of a plurality of cascaded cylindrically-shaped tube sections that are mechanically joined or bonded to one another end-to-end while retaining the internal dimensions of the tube.
4. The acoustic traveling wave tube system of claim 1 , wherein, for wideband non-resonant acoustic applications, the ratio of a circumference of the aperture of the acoustic traveling wave tube to a wavelength at the lowest frequency of the shaped directional acoustic wave to be propagated is at least 3 and a length of the acoustic traveling wave is a multiple of 4 times the axial spacing of the excitation rings.
5. The acoustic traveling wave tube system of claim 1 , wherein, for resonant acoustic applications, the ratio of a circumference of the aperture of the acoustic traveling wave tube to a wavelength at the lowest frequency of the shaped directional acoustic wave to be propagated is at least 3 and the length of the tube is:
L
≈
c
[
2
n
-
1
4
f
n
]
where
c is the speed of sound in the tube,
f, is the natural resonant frequency of the tube (c/4L), and
n is an integer greater than zero.
6. The acoustic traveling wave tube system of claim 1 , wherein each of the plurality of excitation rings is an acoustic transducer of a piezoelectric/electrostrictive material.
7. The acoustic traveling wave tube system of claim 6 , wherein the plurality of excitation rings are spaced at intervals of a maximum of one quarter acoustic wavelength of the highest frequency to be generated.
8. The acoustic traveling wave tube system of claim 1 , wherein the number of excitation rings and the order in which they are energized by the microprocessor along the length of the acoustic traveling wave tube determines the frequency of the directional acoustic wave.
9. The acoustic traveling wave tube system of claim 1 , wherein the shaped directional acoustic wave is formed without any mechanical movements within the acoustic traveling wave tube.
10. The acoustic traveling wave tube system of claim 1 , wherein the system time phases the directional acoustic wave output by two or more acoustic traveling wave tubes to constructively beam steer the directional acoustic wave.
11. The method of claim 10 , wherein the time phasing includes quadrature differential time phasing.
12. An acoustic traveling wave tube system for propagating a directional acoustic wave, the system comprising:
a sheet of carbon nanotube material;
a plurality of excitation rings formed by lengths of carbon nanotube material at predetermined intervals on one surface, wherein the lengths of carbon nanotube material forming the plurality of excitation rings on one surface of a cylindrically-shaped tube;
a load on one end of the tube;
a power amplifier;
an acoustic signal equalizer;
a communications link; and
a microprocessor having a database containing a plurality of waveforms representative of acoustic signals,
wherein the microprocessor energizes one of the plurality of carbon nanotube excitation rings to form an acoustic wave, sequentially energizes one or more of the remaining excitation rings along the length of the tube to amplify the acoustic wave as the acoustic wave travels along the length of the tube, and propagates the acoustic wave from an end of the tube opposite the load as a shaped directional acoustic wave.
13. The acoustic traveling wave tube system of claim 12 , wherein the cylindrically-shaped acoustic traveling wave tube is formed of a lightweight rigid material selected from the group consisting of thermoplastics, thermoplastic laminates, structural composite materials, metals, wood and graphine.
14. The acoustic traveling wave tube system of claim 12 , wherein, for wideband non-resonant acoustic applications, the ratio of a circumference of the aperture of the acoustic traveling wave tube to a wavelength at the lowest frequency of the shaped directional acoustic wave to be propagated is at least 3 and a length of the acoustic traveling wave is a multiple of 4 times the axial spacing of the excitation rings.
15. The acoustic traveling wave tube system of claim 12 , wherein, for resonant acoustic applications, the ratio of a circumference of the aperture of the acoustic traveling wave tube to a wavelength at the lowest frequency of the shaped directional acoustic wave to be propagated is at least 3 and the length of the tube is:
L
≈
c
[
2
n
-
1
4
f
n
]
where
c is the speed of sound in the tube,
f n is the natural resonant frequency of the tube (c/4L), and
n is an integer greater than zero.
16. The acoustic travelling wave tube system of claim 12 , wherein each of the plurality of excitation rings of carbon nanotube material is mechanically integrated into the cylindrically-shaped tube.
17. The acoustic traveling wave tube system of claim 12 , wherein each of the plurality of excitation rings of carbon nanotube material is attached to an outer surface of a cylindrically-shaped tube.
18. The acoustic traveling wave tube system of claim 12 , wherein each of the plurality of excitation rings of carbon nanotube material is attached to an inner surface of a cylindrically-shaped tube.
19. The acoustic traveling wave tube system of claim 12 , wherein the plurality of carbon nanotube excitation rings are formed at intervals of a maximum of one quarter acoustic wavelength of the highest frequency to be generated.
20. The acoustic traveling wave tube system of claim 12 , wherein the number of excitation rings and the order in which they are energized by the microprocessor along the length of the acoustic traveling wave tube determines the frequency of the directional acoustic wave.
21. The acoustic traveling wave tube system of claim 12 , wherein the shaped directional acoustic wave is formed without any mechanical movements within the acoustic traveling wave tube.
22. The acoustic traveling wave tube system of claim 12 , wherein the system time phases the directional acoustic wave output by two or more acoustic traveling wave tubes to constructively beam steer the directional acoustic wave.
23. The method of claim 22 , wherein the time phasing includes quadrature differential time phasing.