WO2006028609A2

WO2006028609A2 - Acoustic driver assembly with modified head mass contact surface

Info

Publication number: WO2006028609A2
Application number: PCT/US2005/027035
Authority: WO
Inventors: Ross Alan Tessien; Dario Felipe Gaitan; Daniel A. Phillips; Brant James Callahan; David G. Beck
Original assignee: Impulse Devices, Inc.
Priority date: 2004-09-01
Filing date: 2005-07-28
Publication date: 2006-03-16
Also published as: WO2006028609A3

Abstract

An acoustic driver assembly for use with any of a variety of cavitation chamber configurations, including spherical, cylindrical and chambers that include at least one flat coupling surface, is provided. The acoustic driver assembly includes a transducer assembly (700) had mass (705) and eight mass (207). The end surface of the head mass is shaped to achieve the desired region of contact between the driver assembly and the cavitation chamber. The end or surface can be shaped to define a ring of contact, a centrally located contact region, or spherically shaped with a curvature that matches the curvatureof the spherical capitation chamber to which it is attached.

Description

Acoustic Driver Assembly With Modified Head Mass Contact Surface

FIELD OF THE INVENTION

The present invention relates generally to sonoluminescence and, more particularly, to an acoustic driver assembly for use with a sonoluminescence cavitation chamber.

BACKGROUND OF THE INVENTION

Sonoluminescence is a well-known phenomena discovered in the 1930's in which light is generated when a liquid is cavitated. Although a variety of techniques for cavitating the liquid are known (e.g., spark discharge, laser pulse, flowing the liquid through a Venturi tube), one of the most common techniques is through the application of high intensity sound waves.

In essence, the cavitation process consists of three stages; bubble formation, growth and subsequent collapse. The bubble or bubbles cavitated during this process absorb the applied energy, for example sound energy, and then release the energy in the form of light emission during an extremely brief period of time. The intensity of the generated light depends on a variety of factors including the physical properties of the liquid (e.g., density, surface tension, vapor pressure, chemical structure, temperature, hydrostatic pressure, etc.) and the applied energy (e.g., sound wave amplitude, sound wave frequency, etc.).

Although it is generally recognized that during the collapse of a cavitating bubble extremely high temperature plasmas are developed, leading to the observed sonoluminescence effect, many aspects of the phenomena have not yet been characterized. As such, the phenomena is at the heart of a considerable amount of research as scientists attempt to not only completely characterize the phenomena (e.g., effects of pressure on the cavitating medium), but also its many applications (e.g., sonochemistry, chemical detoxification, ultrasonic cleaning, etc.).

Although acoustic drivers are commonly used to drive the cavitation process, there is little information about methods of coupling the acoustic energy to the cavitation chamber. For example, in an article entitled Ambient Pressure Effect on Single-Bubble Sonoluminescence by Dan et al. published in vol. 83, no. 9 of Physical Review Letters, the authors describe their study of the effects of ambient pressure on bubble dynamics and single bubble sonoluminescence. Although the authors describe their experimental apparatus in some detail, they only disclose that a piezoelectric transducer was used at the fundamental frequency of the chamber, not how the transducer couples its energy into the chamber. U.S. Patent No. 4,333,796 discloses a cavitation chamber that is generally cylindrical although the inventors note that other shapes, such as spherical, can also be used. As disclosed, the chamber is comprised of a refractory metal such as tungsten, titanium, molybdenum, rhenium or some alloy thereof and the cavitation medium is a liquid metal such as lithium or an alloy thereof. Surrounding the cavitation chamber is a housing which is purportedly used as a neutron and tritium shield. Projecting through both the outer housing and the cavitation chamber walls are a number of acoustic horns, each of the acoustic horns being coupled to a transducer which supplies the mechanical energy to the associated horn. The specification only discloses that the horns, through the use of flanges, are secured to the chamber/housing walls in such a way as to provide a seal and that the transducers are mounted to the outer ends of the horns.

U.S. Patent No. 5,658,534 discloses a sonochemical apparatus consisting of a stainless steel tube about which ultrasonic transducers are affixed. The patent provides considerable detail as to the method of coupling the transducers to the tube. In particular, the patent discloses a transducer fixed to a cylindrical half-wavelength coupler by a stud, the coupler being clamped within a stainless steel collar welded to the outside of the sonochemical tube. The collars allow circulation of oil through the collar and an external heat exchanger. The abutting faces of the coupler and the transducer assembly are smooth and flat. The energy produced by the transducer passes through the coupler into the oil and then from the oil into the wall of the sonochemical tube.

U.S. Patent No. 5,659,173 discloses a sonoluminescence system that uses a transparent spherical flask. The spherical flask is not described in detail, although the specification discloses that flasks of Pyrex®, Kontes®, and glass were used with sizes ranging from 10 milliliters to 5 liters. The drivers as well as a microphone piezoelectric were simply epoxied to the exterior surface of the chamber.

U.S. Patent No. 5,858,104 discloses a shock wave chamber partially filled with a liquid. The remaining portion of the chamber is filled with gas which can be pressurized by a connected pressure source. Acoustic transducers are used to position an object within the chamber while another transducer delivers a compressional acoustic shock wave into the liquid. A flexible membrane separating the liquid from the gas reflects the compressional shock wave as a dilation wave focused on the location of the object about which a bubble is formed. The patent simply discloses that the transducers are mounted in the chamber walls without stating how the transducers are to be mounted.

U.S. Patent No. 5,994,818 discloses a transducer assembly for use with tubular resonator cavity rather than a cavitation chamber. The assembly includes a piezoelectric transducer coupled to a cylindrical shaped transducer block. The transducer block is coupled via a central threaded bolt to a wave guide which, in turn, is coupled to the tubular resonator cavity. The transducer, transducer block, wave guide and resonator cavity are co-axial along a common central longitudinal axis. The outer surface of the end of the wave guide and the inner surface of the end of the resonator cavity are each threaded, thus allowing the wave guide to be threadably and rigidly coupled to the resonator cavity.

U.S. Patent No. 6,361,747 discloses an acoustic cavitation reactor in which the reactor chamber is comprised of a flexible tube. The liquid to be treated circulates through the tube. Electroacoustic transducers are radially and uniformly distributed around the tube, each of the electroacoustic transducers having a prismatic bar shape. A film of lubricant is interposed between the transducer heads and the wall of the tube to help couple the acoustic energy into the tube.

PCT Application No. US00/32092 discloses several driver assembly configurations for use with a solid cavitation reactor. The disclosed reactor system is comprised of a solid spherical reactor with multiple integral extensions surrounded by a high pressure enclosure. Individual driver assemblies are coupled to each of the reactor's integral extensions, the coupling means sealed to the reactor's enclosure in order to maintain the high pressure characteristics of the enclosure.

SUMMARY OF THE INVENTION The present invention provides an acoustic driver assembly for use with any of a variety of cavitation chamber configurations, including spherical and cylindrical chambers as well as chambers that include at least one flat coupling surface. The acoustic driver assembly includes a transducer assembly with at least one piezo-electric transducer, a head mass and a tail mass. The end surface of the head mass is shaped to achieve the desired region of contact between the driver assembly and the cavitation chamber.

In one embodiment of the invention, the shape of the end surface of the head mass defines a ring of contact. Any of a variety of head mass end surface shapes can be used to achieve the desired contact ring. Exemplary head mass end surface shapes include a curved end surface (e.g., concave) and a stepped end surface in which the inner portion of the end surface is recessed relative to an outer, or perimeter, portion of the end surface.

In another embodiment of the invention, the shape of the end surface of the head mass defines a centrally located contact region. Any of a variety of head mass end surface shapes can be used to achieve the desired contact ring. Exemplary head mass end surface shapes include a curved end surface (e.g., convex), a tapered end surface, and a stepped end surface in which the inner portion of the end surface extends beyond the outer, or perimeter, portion of the end surface.

In another embodiment of the invention, the end surface of the head mass is. spherically shaped with a curvature that matches the curvature of the spherical cavitation chamber to which it is attached.

In one embodiment the driver assembly is attached to the exterior surface of the cavitation chamber with a threaded means (e.g., all-thread/nut assembly, bolt, etc.). The same threaded means is used to assemble the driver. In an alternate embodiment, a pair of threaded means is used, one to hold together the tail mass, transducer assembly and head mass and one to attach the driver assembly to the cavitation chamber. In another alternate embodiment, a threaded means is used to assemble the driver, the threaded means being threaded into the head mass. The driver assembly is attached to the cavitation chamber by forming a permanent or semi-permanent joint between the head mass of the driver assembly and the cavitation chamber wall. The permanent or semi-permanent joint can be comprised of an epoxy bond joint, a braze joint, a weld joint, a diffusion bond joint, or other means. In yet another alternate embodiment, the head mass is comprised of a pair of head mass portions that are coupled together with an all- thread. The driver assembly is held together by coupling the driver components to one of the head mass portions using a threaded means. The second head mass portion is attached to the cavitation chamber wall with an all-thread, an epoxy bond joint, a braze joint, a weld joint, a diffusion bond joint, or other means.

In at least one embodiment, a void filling material is interposed between one or more pairs of adjacent surfaces of the driver assembly and/or the driver assembly and the exterior surface of the cavitation chamber.

A further understanding of the nature and advantages of the present invention may be realized by reference to the remaining portions of the specification and the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a perspective view of a driver assembly;

Fig. 2 is a cross-sectional view of a driver assembly fabricated in accordance with the invention and attached to a spherical cavitation chamber; Fig. 3 is a cross-sectional view of an alternate driver assembly in which the head mass coupling means is independent of the driver assembly coupling means;

Fig. 4 is a cross-sectional view of an alternate driver assembly in which the head mass is semi-permanently or permanently coupled to the cavitation chamber exterior surface; Fig. 5 is a cross-sectional view of an alternate driver assembly in which the head mass is comprised of a first portion semi-permanently or peπnanently coupled to the cavitation chamber exterior surface and a second portion associated with the driver assembly;

Fig. 6 is a cross-sectional view of an alternate embodiment of the invention providing a contact ring between the driver assembly and the cavitation chamber wall, the embodiment of Fig. 6 shown attached to a flat cavitation chamber wall;

Fig. 7 is a cross-sectional view of a driver assembly similar to that shown in Fig. 6 with an increased ring of contact area between the driver head mass and the flat cavitation chamber wall; Fig. 8 is a cross-sectional view of a driver assembly similar to that shown in Fig.

6 attached to a cylindrically shaped cavitation chamber, the view presented in Fig. 8 being along the axis of the cylindrical cavitation chamber;

Fig. 9 is an orthogonal cross-sectional view of the embodiment shown in Fig. 8;

Fig. 10 is a cross-sectional view of a driver assembly similar to that shown in Fig. 8 with an increased ring of contact area between the driver head mass and the cylindrical cavitation chamber wall;

Fig. 11 is an orthogonal cross-sectional view of the embodiment shown in Fig. 10;

Fig. 12 is a perspective view of a head mass similar to the head mass of the driver assembly shown in Figs. 8-11;

Fig. 13 is a cross-sectional view of a driver assembly similar to that shown in Fig. 6 attached to a spherically shaped cavitation chamber;

Fig. 14 is a cross-sectional view of a driver assembly similar to that shown in Fig. 13 with an increased ring of contact area between the driver head mass and the cavitation chamber wall;

Fig. 15 is a cross-sectional view of a driver assembly in which the area of the contact ring between the driver head mass and the flat cavitation chamber wall is controlled by varying the area of a stepped contact surface;

Fig. 16 is a cross-sectional view of an embodiment of the invention in which a driver assembly similar to that of Fig. 15 is attached to a cylindrically shaped cavitation chamber, the view presented in Fig. 16 being along the axis of the cylindrical cavitation chamber;

Fig. 17 is an orthogonal cross-sectional view of the embodiment shown in Fig. 16; Fig. 18 is a cross-sectional view of an embodiment of the invention in which a driver assembly similar to that of Fig. 16, except for the use of a shaped contact surface, is attached to a cylindrically shaped cavitation chamber, the view presented in Fig. 18 being along the axis of the cylindrical cavitation chamber; Fig. 19 is an orthogonal cross-sectional view of the embodiment shown in Fig.

18;

Fig. 20 is a cross-sectional view of an embodiment of the invention in which a driver assembly similar to that of Fig. 15 is attached to a spherically shaped cavitation chamber;

Fig. 21 is a cross-sectional view of an embodiment of the invention in which a driver assembly similar to that of Fig. 15, except for the use of a shaped contact surface, is attached to a spherically shaped cavitation chamber;

Fig. 22 is a cross-sectional view of an assembly illustrating an alternate means of attaching any of the driver assemblies of Figs. 6-21 to a cavitation chamber wall;

Fig. 23 is a cross-sectional view of an assembly illustrating an alternate means of attaching any of the driver assemblies of Figs. 6-21 to a cavitation chamber wall;

Fig. 24 is a cross-sectional view of an assembly illustrating an alternate means of attaching any of the driver assemblies of Figs. 6-21 to a cavitation chamber wall;

Fig. 25 is a cross-sectional view of an assembly illustrating an alternate means of attaching any of the driver assemblies of Figs. 6-21 to a cavitation chamber wall; Fig. 26 is a cross-sectional view of an alternate embodiment of the invention providing a centrally located region of contact between the driver assembly and the cavitation chamber wall, the embodiment of Fig. 26 utilizing a flat head mass contacting surface and shown attached to a spherical cavitation chamber wall;

Fig. 27 is a cross-sectional view of an embodiment similar to that shown in Fig. 26, except that the contacting surface of the head mass is curved with a curvature less than that of the external surface of the spherical cavitation chamber wall to which it is attached;

Fig. 28 is a cross-sectional view of an embodiment similar to that shown in Fig. 27, except that the curvature of the contacting surface of the head mass is inverted;

Fig. 29 is a cross-sectional view an embodiment similar to that of Fig. 26, the embodiment of Fig. 29 shown attached to a flat cavitation chamber wall;

Fig. 30 is a cross-sectional view of an embodiment, similar to that of Fig. 26, with a stepped contacting surface;

Fig. 31 is a cross-sectional view of an embodiment similar to that shown in Figs. 28 and 29, attached to a cylindrically shaped cavitation chamber, the view presented in Fig. 31 being along the axis of the cylindrical cavitation chamber; Fig. 32 is an orthogonal cross-sectional view of the embodiment shown in Fig. 31;

Fig. 33 is a cross-sectional view of an embodiment similar to that shown in Fig. 30, attached to a cylindrically shaped cavitation chamber, the view presented in Fig. 33 being along the axis of the cylindrical cavitation chamber;

Fig. 34 is an orthogonal cross-sectional view of the embodiment shown in Fig. 33;

Fig. 35 is a cross-sectional view of an embodiment, similar to that shown in Fig. 33, with a shaped contact surface, the view presented in Fig. 35 being along the axis of the cylindrical cavitation chamber;

Fig. 36 is an orthogonal cross-sectional view of the embodiment shown in Fig. 35;

Fig. 37 is a cross-sectional view of a driver assembly utilizing a tapered head mass to achieve a centrally located contact area between the head mass and a flat cavitation chamber wall;

Fig. 38 is a cross-sectional view of a driver assembly utilizing a tapered head mass with curved side walls to achieve a centrally located contact area between the head mass and a flat cavitation chamber wall;

Fig. 39 is a cross-sectional view of a driver assembly utilizing a head mass with both a stepped end surface and tapered side surfaces;

Fig. 40 is a cross-sectional view of a driver assembly similar to that of Fig. 37, attached to a cylindrical cavitation chamber, the view presented in Fig. 40 being along the axis of the cylindrical cavitation chamber;

Fig. 41 is an orthogonal cross-sectional view of the embodiment shown in Fig. 40;

Fig. 42 is a cross-sectional view of a driver assembly similar to that of Fig. 37 which is attached to a cylindrical cavitation chamber and uses a shaped head mass end surface, the view presented in Fig. 42 being along the axis of the cylindrical cavitation chamber;

Fig. 43 is an orthogonal cross-sectional view of the embodiment shown in Fig. 42;

Fig. 44 is a cross-sectional view of a driver assembly similar to that of Fig. 37, attached to a spherical cavitation chamber;

Fig. 45 is a cross-sectional view of a driver assembly and spherical chamber similar to that illustrated in Fig. 44, except that the end surface of the tapered head mass is shaped; Fig. 46 is a cross-sectional view of an assembly illustrating an alternate means of attaching any of the driver assemblies of Figs. 26-45 to a cavitation chamber wall;

Fig. 47 is a cross-sectional view of an assembly illustrating an alternate means of attaching any of the driver assemblies of Figs. 26-45 to a cavitation chamber wall; Fig. 48 is a cross-sectional view of an assembly illustrating an alternate means of attaching any of the driver assemblies of Figs. 26-45 to a cavitation chamber wall; and

Fig. 49 is a cross-sectional view of an assembly illustrating an alternate means of attaching any of the driver assemblies of Figs. 26-45 to a cavitation chamber wall.

DESCRIPTION OF THE SPECIFIC EMBODIMENTS Fig. 1 is a perspective view of a driver assembly 100. Preferably piezo-electric transducers are used in driver 100 although magnetostrictive transducers can also be used, magnetostrictive transducers typically preferred when lower frequencies are desired. A combination of piezo-electric and magnetostrictive transducers can also be used, for example as a means of providing greater frequency bandwidths. Although driver assembly 100 can use a single piezo-electric transducer, preferably assembly 100 uses a pair of piezo-electric transducer rings 101 and 102 poled in opposite directions. By using a pair of transducers in which the adjacent surfaces of the two crystals have the same polarity, potential grounding problems are minimized. An electrode disc 103 is located between transducer rings 101 and 102 which, during operation, is coupled to the driver power amplifier 105.

The transducer pair is sandwiched between a head mass 107 and a tail mass 109. In one embodiment both head mass 107 and tail mass 109 are fabricated from stainless steel and are of equal mass. In alternate embodiments head mass 107 and tail mass 109 are fabricated from different materials. In yet other alternate embodiments, head mass 107 and tail mass 109 have different masses and/or different mass diameters and/or different mass lengths. For example tail mass 109 can be much larger than head mass 107.

Preferably driver 100 is assembled about a centrally located all-thread 111 which is screwed directly into the wall of the cavitation chamber (not shown). A cap nut 113 holds the assembly together. In a preferred embodiment, all-thread 111 does not pass through the entire chamber wall, thus leaving the internal surface of the cavitation chamber smooth. This method of attachment has the additional benefit of insuring that there are neither gas nor liquid leaks at the point of driver attachment. In an alternate embodiment, for example with thin walled chambers, the threaded hole to which all-thread 111 is coupled passes through the entire chamber wall. Typically in such an embodiment all-thread 111 is sealed into place with an epoxy or other suitable sealant. Alternately all-thread 111 can be welded or brazed to the chamber wall. It is understood that all-thread 111 and cap nut 113 can be replaced with a bolt or other means of attachment. An insulating sleeve, not viewable in Fig. 1, isolates all-thread 111, preventing it from shorting electrode 103.

For purposes of illustration only, a typical driver assembly is approximately 2.5 inches in diameter with a head mass and a tail mass each weighing approximately 5 pounds. Both the head mass and the tail mass may be fabricated from 17-4 PH stainless steel. Suitable piezo-electric transducers are fabricated by Channel Industries of Santa Barbara, California. If the driver assembly is attached to the chamber with an all-thread, the all-thread may be on the order of a 0.5 inch all-thread and the assembly can be tightened to a level of 120 ft-lbs. If an insulating sleeve is used, as preferred, it is typically fabricated from Teflon.

The cavitation chamber to which the driver is attached can be of any regular or irregular shape, although typically the cavitation chamber is spherical, cylindrical, or rectangular in shape. Additionally, it should be appreciated that the invention is not limited to a particular outside chamber diameter, inside chamber diameter or chamber material. Fig.2 is a cross-sectional view of a preferred embodiment of driver assembly

200 attached to a wall 201 of a spherical cavitation chamber. For illustration simplicity, only a portion of the cavitation chamber is shown. It should be understood that driver assembly 200 is attached to the exterior surface 203 of chamber wall 201. In addition to shaped head mass 205, driver assembly 200 includes a tail mass 207, one or more transducers (e.g., a pair of piezo- electric transducers 209/211 are shown), and means such as an electrode ring 213 for coupling the transducer(s) to a driver amplifier 215. In the illustrated embodiment, an all-thread 217 and a nut 219 are used to mount driver assembly 200 to chamber wall 201. Alternately a bolt or other means can be used to mount driver assembly 200 to wall 201. An insulating sleeve 221 isolates all-thread 217. End surface 223 of driver assembly 200 is spherically shaped with a curvature matching that of external chamber surface 203. This design achieves the efficient transfer of acoustic energy into the spherical cavitation chamber.

In an alternate embodiment shown in Fig. 3, the driver is assembled about a first threaded means 301 (e.g., all-thread or bolt) which is threaded into head mass 302. Coupling means, for example an all-thread member 303 as shown, is used to couple driver assembly 300 to wall 201 of the spherical chamber. The principal benefit of this configuration is that the driver assembly is independent of the driver-chamber coupling means. As a result, a driver can be attached to, or detached from, a cavitation chamber without disassembling the actual driver assembly. This approach is especially beneficial given the susceptibility of piezo-electric crystals to damage. Fig. 4 is an illustration of an alternate embodiment in which the head mass of the driver assembly is semi-pennanently or permanently coupled to the cavitation chamber exterior surface. As shown, head mass 401 is attached to chamber exterior surface 203 along joint 403. Joint 403 can be comprised of an epoxy (or other adhesive) bond joint, a braze or weld joint, a diffusion bond joint, or other means. For small drivers bonding is typically adequate while for larger drivers, due to their mass and the vibration inherent in the assembly when operating, a more permanent coupling technique such as brazing, welding or diffusion bonding is preferred. As the head mass in this embodiment is permanently coupled to the chamber surface, a threaded means such as all-thread 303 is not required although the embodiment does require a driver assembly threaded means 301.

If desired, and as a means of allowing the driver assembly to be assembled/disassembled separately from the chamber/head mass assembly, a two-piece head mass assembly can be used as illustrated in Fig. 5. As shown, a first head mass portion 501 is attached to chamber exterior surface 203 at a joint 403, for example utilizing a braze joint, weld joint, bond joint with an adhesive (e.g., epoxy) or diffusion bond joint as noted above, while a second head mass portion 503 is coupled to the driver assembly via threaded means 505 (e.g., all-thread/nut arrangement or bolt). A second threaded means 507 couples head mass portion 501 to head mass portion 503. It will be appreciated that first head mass portion 501 can also be attached to chamber wall 201 using an all-thread (e.g., all-thread 303 shown in Fig. 3), rather than a permanent or semi-permanent means.

Figs. 6-25 illustrate embodiments of the invention in which the end surface of the head mass is shaped so that only a ring of contact is made between an outward portion of the driver's head mass end surface and the cavitation chamber to which the driver is attached. Accordingly the area of the ring of contact is less than the area of the head mass end surface. Fig. 6 is a cross-sectional view of a driver 600 attached to a flat cavitation chamber wall 601. For illustration simplicity, only a portion of the cavitation chamber is shown. It should be understood that driver assembly 600 is attached to the exterior surface 603 of chamber wall 601. It should also be understood that chamber wall 601 may correspond to a square chamber, rectangular chamber, or other chamber shape which includes at least one flat wall. In addition to shaped head mass 605, driver assembly 600 includes a tail mass 207, one or more transducers (e.g., a pair of piezo-electric transducers 209/211 are shown), and means such as an electrode ring 213 for coupling the transducer(s) to a driver amplifier 215. In the illustrated embodiment, an all-thread 217 and a nut 219 are used to mount driver assembly 600 to chamber wall 601. Alternately a bolt or other means can be used to mount driver assembly 600 to wall 601. An insulating sleeve 221 isolates all-thread 217. Due to the curvature of surface 607 of head mass 605, instead of the entire end surface 607 being in contact with the cavitation chamber, there is only a ring of contact 609 between the two surfaces. To improve the contact between the driver and the chamber, in a preferred embodiment illustrated in Fig. 7 the contact area is increased by shaping (e.g., chamfering) the outer edge 701 of end surface 703 of the head mass 705. As in the previous embodiment, this approach limits the contact area to a ring while maintaining a centrally located cavity 707 between the head mass and the chamber surface.

Figs. 8 and 9 are cross-sectional views of a driver assembly similar to that shown in Fig. 6, but in which the cavitation chamber surface is cylindrically shaped. Fig. 8 is a view along the axis of the cylindrical cavitation chamber while Fig. 9 is a view perpendicular to the chamber's axis. As illustrated in these figures, head mass 801 is shaped so that there is a ring of contact 803 between the head mass and the outer surface 805 of cavitation chamber wall 807. If desired, the contact area can be increased by shaping the outer edge 1001 of the end surface 1003 of the head mass 1005 as shown in Figs. 10 and 11 of driver assembly 1000. As with the prior embodiment, Fig. 10 is a view along the axis of the cylindrical cavitation chamber and Fig. 11 is a view perpendicular to the chamber's axis.

Fig. 12 provides a perspective view of a head mass 1200 similar to either head mass 801 or head mass 1005, thus suitable for use with a cylindrical cavitation chamber. In this view, however, the curvature of the end surface 1201 is exaggerated, thereby aiding visualization of the shape of the head mass. It will be appreciated that if the cavitation chamber diameter is sufficiently small relative to the diameter of the driver assembly, end surface 1201 is not exaggerated.

Fig. 13 is cross-sectional view of a driver assembly similar to that shown in Figs. 6, 8 and 9, but in which the cavitation chamber surface is spherically shaped as in Figs. 2-5. As illustrated in Fig. 13, head mass 1301 of assembly 1300 has an end surface 1303 with a curvature that is greater than the spherical curvature of external chamber surface 203. As a result, rather than having the entire end surface being in contact with the external chamber surface 203, only a ring 1305 of contact is made between the two surfaces. If desired, the contact area 1401 can be increased by chamfering the contact area of end surface 1403 of the head mass 1405 as illustrated in Fig. 14.

In addition to the curved surface of the head mass shown in Figs. 6-14, the inventors also envision that the surface of the head mass that is adjacent to the chamber external surface can utilize other shapes to achieve the desired ring of contact between the chamber wall and the driver assembly. For example, the surface of the head mass can be stepped as shown in Figs. 15-21. Fig. 15 is a cross-sectional view of an embodiment of the invention in which driver assembly 1500 is attached to flat exterior surface 603 of flat cavitation chamber wall 601. As in the previous illustrations, only a portion of the cavitation chamber is shown. As previously noted, chamber wall 601 may correspond to a square chamber, rectangular chamber or other chamber shape which includes at least one flat wall. The end surface of head mass 1501 includes at least two different surfaces 1503 and 1505, surface 1505 recessed relative to surface 1503, thereby providing the desired ring of contact 1507 between head mass 1501 and chamber external surface 603.

Figs. 16 and 17 illustrate an embodiment of the invention similar to that shown in Fig. 15, except used with a cylindrically shaped cavitation chamber. Fig. 16 is a view along the axis of the cylindrical cavitation chamber while Fig. 17 is a view perpendicular to the chamber's axis. As shown, head mass 1501 of driver assembly 1500 contacts external chamber surface 805 along ring of contact 1507. If desired, the area of the ring of contact can be increased by shaping the contacting surface of the head mass. For example, Figs. 18 and 19 illustrate a driver assembly 1800 similar to that shown in Figs. 16 and 17 except contacting surface 1801 of head mass 1803 is shaped to increase the contact area. In the illustrated embodiment, surface 1801 is shaped to match the curvature of the cylindrical external surface 805 of cylindrical chamber wall 807. It is understood that surface 1801 can utilize other curvatures in order to achieve the desired contact area. Fig. 20 illustrates the use of a driver assembly similar to that shown in Figs. 15-

17 with a spherically shaped chamber. Due to the symmetry of a spherical chamber, only a single view is required to illustrate the embodiment. As shown, head mass 1501 of driver assembly 1500 contacts external chamber surface 203 of spherical chamber wall 201 along a contact ring of 2001. If desired, the area of the ring of contact can be increased by shaping the contacting surface 2101 of the head mass as illustrated in Fig. 21. Although the curvature of the contacting surface in Fig. 21 matches the curvature of the spherical surface of the chamber, it will be appreciated that other curvatures can be used, thus providing a relatively simple means of controlling the area of the ring of contact between the driver assembly and the spherical chamber. Although the embodiments described above and shown in Figs. 6-21 are shown with either an all-thread/nut or bolt means of attachment, any of these embodiments can also utilize other mounting means. For example, Fig. 22 is an illustration of a driver assembly 2200 similar to that shown in Fig. 6, but in which the driver is assembled about a first threaded means 2201 (e.g., all-thread or bolt) which is threaded into head mass 2203. Coupling means, for example an all-thread member 2205 as shown, is used to couple head mass 2203 to surface 603 of chamber wall 601. Alternately and as illustrated in Fig. 23, the head mass (i.e., head mass 2301) can be semi-permanently or permanently attached to the cavitation chamber at a joint 2303. Joint 2303 can be comprised of an epoxy (or other adhesive) bond joint, a braze or weld joint, a diffusion bond joint, or other means. As with the embodiment illustrated in Fig. 22, the remaining portions of the driver assembly are coupled to the head mass with an all-thread/nut or bolt means.

If desired, and as a means of allowing the driver assembly to be assembled/disassembled separately from the chamber/head mass assembly, a two-piece head mass assembly, such as that illustrated in either Fig. 24 or Fig. 25, can be used. As shown in Fig. 24, a first head mass portion 2401 is coupled to chamber exterior surface 603 using a first threaded means 2403 (e.g., all-thread) while a second head mass portion 2405 is coupled to the driver assembly via a second threaded means 2407 (e.g., all-thread/nut arrangement or bolt). A third threaded means 2409 couples head mass portion 2401 to head mass portion 2405. In a slight modification shown in Fig. 25, first head mass portion 2401 is semi-permanently or permanently attached to the cavitation chamber at a joint 2501 , joint 2501 comprised of an epoxy (or other adhesive) bond joint, a braze or weld joint, a diffusion bond joint, or other means. The principal benefit of the configurations shown in Figs. 24 and 25 is that the driver assembly is independent of the driver-chamber coupling means. As a result, a driver assembly can be attached to, or detached from, a cavitation chamber without disassembling the actual driver assembly. This is especially beneficial given the susceptibility of piezo-electric crystals to damage.

It should be appreciated that although the alternate attachment means illustrated in Figs. 22-25 are shown with a flat cavitation surface, these alternate attachment means can also be utilized with non-flat surfaces such as cylindrical and spherical surfaces. Figs. 26-49 illustrate embodiments of the invention in which the end surface of the head mass is shaped so that only a centrally located contact region is made between a centrally located portion of the head mass of the driver assembly and the cavitation chamber to which the driver is attached. Accordingly the area of the centrally located contact region is less than the area of the head mass end surface. In Fig. 26 driver assembly 2600 is attached to a spherical chamber wall 201. The head mass 2601 of assembly 2600 has an end surface 2603 with a curvature that is less than that of external chamber surface 203. For example, as shown, end surface 2603 is flat, leading to only a small portion 2605 of surface 2603 being in contact with external chamber surface 203. A similar result can be obtained as illustrated in Fig. 27 in which the curvature of surface 2701 is less than that of external surface 203, but more than a flat surface. Alternately, the curvature of surface 2801 of head mass 2803 can be inverted as shown in Fig. 28, also resulting in minimal contact between the two surfaces, the contact area being located around the central portion of the driver assembly.

Fig. 29 is a cross-sectional view of a driver 2900 attached to flat cavitation chamber wall 601. As in the other figures of this specification, only a portion of the cavitation chamber is shown in order to simplify the illustration. As previously noted, chamber wall 601 may correspond to a square chamber, rectangular chamber, or other chamber shape which includes at least one flat wall. Due to the curvature of surface 2901 of head mass 2903, instead of the entire end surface 2901 being in contact with cavitation surface 603, there is only a-region of contact 2905 between the two surfaces, the contact region being centrally located about threaded means 217. The area of the contact region is controlled by varying the curvature of the end surface of the head mass. For example, the contact area can be increased by decreasing the curvature of end surface 2901 of head mass 2903. Alternately, and as shown in Fig. 30, the end surface of the head mass can be stepped, thus providing a centrally located contact region 3001 surrounded by a non-contact area 3003.

Figs. 31 and 32 are cross-sectional views of a driver assembly similar to that shown in Figs. 28 and 29, but in which the cavitation chamber surface is cylindrically shaped. Fig. 31 is a view along the axis of the cylindrical cavitation chamber while Fig. 32 is a view perpendicular to the chamber's axis. As illustrated in these figures, head mass 3101 is shaped so that there is a centrally located contact area 3103 between the head mass and the outer surface 805 of cavitation chamber wall 807.

Figs. 33 and 34 are cross-sectional views of a driver assembly similar to that shown in Fig. 30 with a cylindrically shaped cavitation chamber surface such as that shown in Figs. 31 and 32. As with the prior embodiment, Fig. 33 is a view along the axis of the cylindrical cavitation chamber and Fig. 34 is a view perpendicular to the chamber's axis.

In the embodiments illustrated in Figs. 31/32 and Figs. 33/34, the contact region is not symmetrical due to the cylindrical curvature of the chamber. In the case of the embodiment illustrated in Figs. 31/32, the extent of the non-symmetry depends on the relative curvatures of the cylindrically curved chamber and the spherically curved end surface 3105. In the case of the embodiment illustrated in Figs. 33/34, the extent of the non-symmetry depends on the curvature of the cylindrically curved chamber as well as the diameter of the contact surface 3301 of head mass 3303. In order to achieve a symmetrical contact surface, preferably the stepped down contact region of the end surface of the head mass is cylindrically shaped to match the surface 805 of the chamber (i.e., surface 3501 of head mass 3503 illustrated in Figs. 35 and 36). In addition to curved and stepped head mass end surfaces, other shapes are clearly envisioned by the inventors which achieve the desired centrally located contact region between the head mass and the cavitation chamber. For example, Fig. 37 is a cross-sectional view of a driver assembly 3700 utilizing a tapered head mass 3701, the assembly being attached to flat cavitation wall 601. Side surface 3703 of the head mass tapers down from head mass side wall 3705 to end surface 3707. Alternately, side surface 3703 can taper down directly from the head mass end surface 3709 to end surface 3707, thereby eliminating side wall 3705 (not shown).

Fig. 38 is a cross-sectional view of an alternate embodiment in which driver assembly 3800 utilizes a tapered head mass 3801 similar to that shown in Fig. 37, except for the use of curved side surfaces 3803 to define contact area 3805.

Fig. 39 is a cross-sectional view of an alternate embodiment in which driver assembly 3900 utilizes a head mass 3901 that includes both a step-down from head mass diameter 3903 and tapered side walls 3905. Although linear side walls 3905 are shown, side walls 3905 could also be curved, for example as illustrated relative to the embodiment of Fig. 38.

A tapered head mass such as those illustrated in Figs. 37-39 can also be used with non-flat cavitation chamber walls. For example, Figs. 40 and 41 are cross-sectional views of a driver assembly similar to that shown in Fig. 37, but in which the cavitation chamber surface is cylindrically shaped. Fig. 40 is a view along the axis of the cylindrical cavitation chamber and Fig. 41 is a view perpendicular to the chamber's axis. As illustrated in these figures, end surface 4001 of tapered head mass 4003 forms a central contact region between the head mass and the outer surface 805 of cavitation chamber wall 807.

Figs. 42 and 43 are cross-sectional views of a driver assembly similar to that shown in Figs. 40 and 41, except that end surface 4201 of tapered head mass 4203 is shaped to increase the contact area between the head mass and the cylindrically shaped cavitation chamber. As with the prior embodiment, Fig. 42 is a view along the axis of the cylindrical cavitation chamber and Fig. 43 is a view perpendicular to the chamber's axis.

Fig. 44 illustrates the use of a driver assembly such as that shown in Fig. 37 with a spherically shaped chamber wall 201. Due to the symmetry of a spherical chamber, only a single view is required to illustrate the embodiment. As shown, head mass 4401 of driver assembly 4400 contacts external chamber surface 203 of chamber wall 201 along a centrally located contact area 4403. If desired, the contact area between the head mass and the spherical chamber can be increased by shaping the contact surface of the head mass as illustrated in Fig. 45 (e.g., surface 4501). It should be appreciated that although only a driver assembly similar to that of Fig. 37 is shown attached to cylindrical and spherical chambers (i.e., Figs. 40-45), other tapered head masses such as those shown in Figs. 38 and 39 can similarly be used with cylindrical and spherical chambers. Additionally, it should be appreciated that although the curvature of the contacting surface in Figs. 35/36, 42/43 and 45 match the curvature of the chamber surface to which the driver is attached, other curvatures can be used, thus providing a relatively simple means of controlling the contact area between the driver assembly and the chamber.

Although the embodiments described in Figs. 26-45, as illustrated, utilize either an all-thread/nut or bolt means of attachment, any of these embodiments can also utilize other mounting means. For example, Fig. 46 is an illustration of a driver assembly 4600 similar to that shown in Fig. 30, but in which the driver is assembled about a first threaded means 4601 (e.g., all-thread or bolt) which is threaded into head mass 4603. Coupling means, for example an all-thread member 4605 as shown, is used to couple head mass 4603 to surface 603 of chamber wall 601. Alternately and as illustrated in Fig. 47, the head mass (i.e., head mass 4701) can be semi-permanently or permanently attached to the cavitation chamber at a j oint 4703. Joint 4703 can be comprised of an epoxy (or other adhesive) bond joint, a braze or weld joint, a diffusion bond joint, or other means. As with the embodiment illustrated in Fig. 46, the remaining portions of the driver assembly are coupled to the head mass with an all-thread/nut or bolt means. If desired, and as a means of allowing the driver assembly to be assembled/disassembled separately from the chamber/head mass assembly, a two-piece head mass assembly can be used as illustrated in Figs. 48 and 49. As shown in Fig. 48, a first head mass portion 4801 is coupled to chamber exterior surface 603 using a first threaded means 4803 (e.g., all-thread) while a second head mass portion 4805 is coupled to the driver assembly via a second threaded means 4807 (e.g., all-thread/nut arrangement or bolt). A third threaded means 4809 couples head mass portion 4801 to head mass portion 4805. In a slight modification shown in Fig. 49, first head mass portion 4801 is semi-permanently or permanently attached to the cavitation chamber at a joint 4901, joint 4901 comprised of an epoxy (or other adhesive) bond joint, a braze or weld joint, a diffusion bond joint, or other means. The principal benefit of the configurations shown in Figs. 48 and 49 is that the driver assembly is independent of the driver-chamber coupling means. As a result, a driver assembly can be attached to, or detached from, a cavitation chamber without disassembling the actual driver assembly. This is especially beneficial given the susceptibility of piezo-electric crystals to damage. It should be appreciated that although the alternate attachment means illustrated in Figs. 46-49 are shown with a flat cavitation surface, these alternate attachment means can also be utilized with non-flat surfaces such as cylindrical and spherical surfaces.

Although not required by the invention, preferably void filling material is included between some or all adjacent pairs of surfaces of the driver assembly and/or the driver assembly and the exterior surface of the cavitation chamber, thereby improving the overall coupling efficiency and operation of the driver. Suitable void filling material should be sufficiently compressible to fill the voids or surface imperfections of the adjacent surfaces while not being so compressible as to overly dampen the acoustic energy supplied by the transducers. Preferably the void filling material is a high viscosity grease, although wax, very soft metals (e.g., solder), or other materials can be used.

As will be understood by those familiar with the art, the present invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. Accordingly, the disclosures and descriptions herein are intended to be illustrative, but not limiting, of the scope of the invention which is set forth in the following claims.

Claims

WHAT IS CLAIMED IS:

1. A cavitation system, comprising: a cavitation chamber; an acoustic driver assembly coupled to a wall of said cavitation chamber, wherein said cavitation chamber wall comprises an external surface, said acoustic driver assembly comprising: a piezo-electric transducer assembly comprising at least one piezo- electric transducer; a tail mass adjacent to a first side of said piezo-electric transducer assembly; a head mass with a first end surface and a second end surface, wherein said first end surface of said head mass is adjacent to a second side of said piezo-electric transducer assembly and said second end surface of said head mass is adjacent to a portion of said external surface, wherein said second end surface of said head mass defines a ring of contact between an outward portion of said second end surface of said head mass and said external surface, wherein a first area corresponding to said ring of contact is less than a second area corresponding to said second end surface; means for assembling said acoustic driver assembly; and means for attaching said acoustic driver assembly to said external surface.

2. The cavitation system of claim 1, wherein said cavitation chamber is a spherical cavitation chamber, wherein said external surface is defined by a first spherical curvature, wherein said second end surface of said head mass has a second spherical curvature, and wherein said second spherical curvature is greater than said first spherical curvature.

3. The cavitation system of claim 1, wherein said cavitation chamber is a spherical cavitation chamber, wherein said external surface is defined by a spherical curvature, wherein a first portion of said second end surface of said head mass is surrounded by a second portion of said second end surface of said head mass, wherein said second portion of said second end surface extends beyond said first portion of said second end surface, and wherein said second portion of said second end surface defines said ring of contact.

4. The cavitation system of claim 1, wherein said external surface is flat and said second end surface of said head mass is curved.

5. The cavitation system of claim 1, wherein said external surface is flat, wherein a first portion of said second end surface of said head mass is surrounded by a second portion of said second end surface of said head mass, wherein said second portion of said second end surface extends beyond said first portion of said second end surface, and wherein said second portion of said second end surface defines said ring of contact.

6. The cavitation system of claim 1, wherein said cavitation chamber is a cylindrical cavitation chamber, and wherein said external surface is defined by a cylindrical curvature and said second end surface of said head mass is curved.

7. The cavitation system of claim 1, wherein said cavitation chamber is a cylindrical cavitation chamber, wherein said external surface is defined by a cylindrical curvature, wherein a first portion of said second end surface of said head mass is surrounded by a second portion of said second end surface of said head mass, wherein said second portion of said second end surface extends beyond said first portion of said second end surface, and wherein said second portion of said second end surface defines said ring of contact.

8. The cavitation system of claim 1, wherein a surface corresponding to said ring of contact is shaped to increase said first area corresponding to said ring of contact.

9. The cavitation system of claim 1, wherein said assembling means and said attaching means comprise a centrally located threaded means coupling said tail mass, said piezo-electric transducer assembly and said head mass to said external surface, wherein said centrally located threaded means is threaded into a corresponding threaded hole in said external surface, wherein said threaded hole extends at least part way through said cavitation chamber wall.

10. The cavitation system of claim 9, said centrally located threaded means further comprising a corresponding threaded nut, wherein said threaded nut compresses said tail mass, said piezo-electric transducer assembly and said head mass against said external surface.

11. The cavitation system of claim 9, wherein said threaded hole extends completely through said cavitation chamber wall.

12. The cavitation system of claim 1, said assembling means further comprising a first centrally located threaded means coupling said tail mass, said piezo-electric transducer assembly and said head mass together, wherein said first centrally located threaded means is threaded into a corresponding threaded hole in said head mass.

13. The cavitation system of claim 12, said first centrally located threaded means further comprising a corresponding threaded nut, wherein said threaded nut compresses said tail mass and said piezo-electric transducer assembly against said head mass.

14. The cavitation system of claim 12, said attaching means further comprising a second centrally located threaded means, wherein a first end portion of said second centrally located threaded means is threaded into said head mass and a second end portion of said second centrally located threaded means is threaded into a corresponding threaded hole in said external surface.

15. The cavitation system of claim 12, said attaching means further comprising an epoxy bond joint.

16. The cavitation system of claim 12, said attaching means further comprising a braze joint.

17. The cavitation system of claim 12, said attaching means further comprising a weld j oint.

18. The cavitation system of claim 12, said attaching means further comprising a diffusion bond j oint.

19. The cavitation system of claim 1, said head mass further comprising a first head mass portion and a second head mass portion, wherein said first head mass portion includes said first end surface and said second head mass portion includes said second end surface, and wherein said assembling means further comprises: a first threaded means coupling said first head mass portion to said second head mass portion; and a second threaded means coupling said tail mass, said piezo-electric transducer assembly and said first head mass portion together, wherein said second threaded means is threaded into a corresponding threaded hole in said first head mass portion.

20. The cavitation system of claim 19, said second threaded means further comprising a corresponding threaded nut, wherein said threaded nut compresses said tail mass and said piezo-electric transducer assembly against said first head mass portion.

21. The cavitation system of claim 19, said attaching means further comprising a third threaded means, wherein a first end portion of said third threaded means is threaded into said second head mass portion and a second end portion of said third threaded means is threaded into a corresponding threaded hole in said external surface.

22. The cavitation system of claim 19, said attaching means further comprising an epoxy bond j oint.

23. The cavitation system of claim 19, said attaching means further comprising a braze j oint.

24. The cavitation system of claim 19, said attaching means further comprising a weld j oint.

25. The cavitation system of claim 19, said attaching means further comprising a diffusion bond j oint.

26. The cavitation system of claim 1, further comprising a void filling material interposed between at least two adjacent contact surfaces of said acoustic driver assembly.

27. The cavitation system of claim 1, further comprising a void filling material interposed between said second surface of said head mass and said external surface.

28. A cavitation system, comprising: a cavitation chamber; an acoustic driver assembly coupled to a wall of said cavitation chamber, wherein said cavitation chamber wall comprises an external surface, said acoustic driver assembly comprising: a piezo-electric transducer assembly comprising at least one piezo- electric transducer; a tail mass adjacent to a first side of said piezo-electric transducer assembly; a head mass with a first end surface and a second end surface, wherein said first end surface of said head mass is adjacent to a second side of said piezo-electric transducer assembly and said second end surface of said head mass is adjacent to a portion of said external surface, wherein said second end surface of said head mass defines a centrally located contact region between a centrally located portion of said second end surface of said head mass and said external surface, wherein a first area corresponding to said centrally located contact region is less than a second area corresponding to said second end surface; means for assembling said acoustic driver assembly; and means for attaching said acoustic driver assembly to said external surface.

29. The cavitation system of claim 28, wherein said cavitation chamber is a spherical cavitation chamber, wherein said external surface is defined by a first spherical curvature, wherein said second end surface of said head mass has a second spherical curvature, and wherein said second spherical curvature is less than said first spherical curvature.

30. The cavitation system of claim 28, wherein said cavitation chamber is a spherical cavitation chamber, wherein said external surface is defined by a spherical curvature, wherein a first portion of said second end surface of said head mass is surrounded by a second portion of said second end surface of said head mass, wherein said first portion of said second end surface extends beyond said second portion of said second end surface, and wherein said first portion of said second end surface defines said centrally located contact region.

31. The cavitation system of claim 28, wherein said cavitation chamber is a spherical cavitation chamber, wherein said external surface is defined by a spherical curvature, wherein a first portion of said second end surface of said head mass is surrounded by a second portion of said second end surface of said head mass, wherein said second end surface is tapered, and wherein said tapered second end surface defines said centrally located contact region.

32. The cavitation system of claim 28, wherein said cavitation chamber is a spherical cavitation chamber, wherein said external surface is defined by a spherical curvature, and wherein said second end surface of said head mass is flat.

33. The cavitation system of claim 28, wherein said external surface is flat and said second end surface of said head mass is curved.

34. The cavitation system of claim 28, wherein said external surface is flat, wherein a first portion of said second end surface of said head mass is surrounded by a second portion of said second end surface of said head mass, wherein said first portion of said second end surface extends beyond said second portion of said second end surface, and wherein said first portion of said second end surface defines said centrally located contact region.

35. The cavitation system of claim 28, wherein said external surface is flat, wherein a first portion of said second end surface of said head mass is surrounded by a second portion of said second end surface of said head mass, wherein said second end surface is tapered, and wherein said tapered second end surface defines said centrally located contact region.

36. The cavitation system of claim 28, wherein said cavitation chamber is a cylindrical cavitation chamber, said external surface is defined by a cylindrical curvature, said second end surface of said head mass is curved, and said curved second end surface defines said centrally located contact region.

37. The cavitation system of claim 28, wherein said cavitation chamber is a cylindrical cavitation chamber, wherein said external surface is defined by a cylindrical curvature, wherein a first portion of said second end surface of said head mass is surrounded by a second portion of said second end surface of said head mass, wherein said first portion of said second end surface extends beyond said second portion of said second end surface, and wherein said first portion of said second end surface defines said centrally located contact region.

38. The cavitation system of claim 28, wherein said cavitation chamber is a cylindrical cavitation chamber, wherein said external surface is defined by a cylindrical curvature, wherein a first portion of said second end surface of said head mass is surrounded by a second portion of said second end surface of said head mass, wherein said second end surface is tapered, and wherein said tapered second end surface defines said centrally located contact region. '

39. The cavitation system of claim 28, wherein a surface corresponding to said centrally located contact region is shaped to increase said first area corresponding to said centrally located contact region.

40. The cavitation system of claim 28, wherein said assembling means and said attaching means comprise a centrally located threaded means coupling said tail mass, said piezo-electric transducer assembly and said head mass to said external surface, wherein said centrally located threaded means is threaded into a corresponding threaded hole in said external surface, wherein said threaded hole extends at least part way through said cavitation chamber wall.

41. The cavitation system of claim 40, said centrally located threaded means fUrther comprising a corresponding threaded nut, wherein said threaded nut compresses said tail mass, said piezo-electric transducer assembly and said head mass against said external surface.

42. The cavitation system of claim 40, wherein said threaded hole extends completely through said cavitation chamber wall.

43. The cavitation system of claim 28, said assembling means further comprising a first centrally located threaded means coupling said tail mass, said piezo-electric transducer assembly and said head mass together, wherein said first centrally located threaded means is threaded into a corresponding threaded hole in said head mass.

44. The cavitation system of claim 43, said first centrally located threaded means further comprising a corresponding threaded nut, wherein said threaded nut compresses said tail mass and said piezo-electric transducer assembly against said head mass.

45. The cavitation system of claim 43, said attaching means further comprising a second centrally located threaded means, wherein a first end portion of said second centrally located threaded means is threaded into said head mass and a second end portion of said second centrally located threaded means is threaded into a corresponding threaded hole in said external surface.

46. The cavitation system of claim 43, said attaching means further comprising an epoxy bond j oint.

47. The cavitation system of claim 43, said attaching means further comprising a braze j oint.

48. The cavitation system of claim 43, said attaching means further comprising a weld j oint.

49. The cavitation system of claim 43, said attaching means further comprising a diffusion bond j oint.

50. The cavitation system of claim 28, said head mass further comprising a first head mass portion and a second head mass portion, wherein said first head mass portion includes said first end surface and said second head mass portion includes said second end surface, and wherein said assembling means further comprises: a first threaded means coupling said first head mass portion to said second head mass portion; and a second threaded means coupling said tail mass, said piezo-electric transducer assembly and said first head mass portion together, wherein said second threaded means is threaded into a corresponding threaded hole in said first head mass portion.

51. The cavitation system of claim 50, said second threaded means further comprising a corresponding threaded nut, wherein said threaded nut compresses said tail mass and said piezo-electric transducer assembly against said first head mass portion.

52. The cavitation system of claim 50, said attaching means further comprising a third threaded means, wherein a first end portion of said third threaded means is threaded into said second head mass portion and a second end portion of said third threaded means is threaded into a corresponding threaded hole in said external surface.

53. The cavitation system of claim 50, said attaching means further comprising an epoxy bond joint.

54. The cavitation system of claim 50, said attaching means further comprising a braze j oint.

55. The cavitation system of claim 50, said attaching means further comprising a weld joint.

56. The cavitation system of claim 50, said attaching means further comprising a diffusion bond j oint.

57. The cavitation system of claim 28, further comprising a void filling material interposed between at least two adjacent contact surfaces of said acoustic driver assembly.

58. The cavitation system of claim 28, further comprising a void filling material interposed between said second surface of said head mass and said external surface.

59. A cavitation system, comprising: a spherical cavitation chamber comprising an external surface defined by a spherical curvature and an internal surface, wherein said spherical cavitation chamber external surface and said spherical cavitation chamber internal surface define a spherical cavitation chamber wall; an acoustic driver assembly coupled to said spherical cavitation chamber wall, said acoustic driver assembly comprising: a piezo-electric transducer assembly comprising at least one piezo- electric transducer; a tail mass adjacent to a first side of said piezo-electric transducer assembly; a head mass with a first end surface and a second end surface, wherein said first end surface of said head mass is adjacent to a second side of said piezo-electric transducer assembly and said second end surface of said head mass is adjacent to a portion of said spherical cavitation chamber external surface, wherein said second end surface of said head mass has a spherical curvature equivalent to said spherical curvature of said spherical cavitation chamber external surface; means for assembling said acoustic driver assembly; and means for attaching said acoustic driver assembly to said spherical cavitation chamber external surface.

60. The cavitation system of claim 59, wherein said assembling means and said attaching means comprise a centrally located threaded means coupling said tail mass, said piezo-electric transducer assembly and said head mass to said spherical cavitation chamber external surface, wherein said centrally located threaded means is threaded into a corresponding threaded hole in said spherical cavitation chamber external surface, wherein said threaded hole extends at least part way through said spherical cavitation chamber wall.

61. The cavitation system of claim 60, said centrally located threaded means further comprising a corresponding threaded nut, wherein said threaded nut compresses said tail mass, said piezo-electric transducer assembly and said head mass against said spherical cavitation chamber external surface.

62. The cavitation system of claim 60, wherein said threaded hole extends completely through said spherical cavitation chamber wall.

63. The cavitation system of claim 59, said assembling means further comprising a first centrally located threaded means coupling said tail mass, said piezo-electric transducer assembly and said head mass together, wherein said first centrally located threaded means is threaded into a corresponding threaded hole in said head mass.

64. The cavitation system of claim 63, said first centrally located threaded means further comprising a corresponding threaded nut, wherein said threaded nut compresses said tail mass and said piezo-electric transducer assembly against said head mass.

65. The cavitation system of claim 63, said attaching means further comprising a second centrally located threaded means, wherein a first end portion of said second centrally located threaded means is threaded into said head mass and a second end portion of said second centrally located threaded means is threaded into a corresponding threaded hole in said spherical cavitation chamber external surface.

66. The cavitation system of claim 63, said attaching means further comprising an epoxy bond j oint.

67. The cavitation system of claim 63, said attaching means further comprising a braze joint.

68. The cavitation system of claim 63, said attaching means further comprising a weld j oint.

69. The cavitation system of claim 63, said attaching means further comprising a diffusion bond j oint.

70. The cavitation system of claim 59, said head mass further comprising a first head mass portion and a second head mass portion, wherein said first head mass portion includes said first end surface and said second head mass portion includes said second end surface, and wherein said assembling means further comprises: a first threaded means coupling said first head mass portion to said second head mass portion; and a second threaded means coupling said tail mass, said piezo-electric transducer assembly and said first head mass portion together, wherein said second threaded means is threaded into a corresponding threaded hole in said first head mass portion.

71. The cavitation system of claim 70, said second threaded means further comprising a corresponding threaded nut, wherein said threaded nut compresses said tail mass and said piezo-electric transducer assembly against said first head mass portion.

72. The cavitation system of claim 70, said attaching means further comprising a third threaded means, wherein a first end portion of said third threaded means is threaded into said second head mass portion and a second end portion of said third threaded means is threaded into a corresponding threaded hole in said spherical cavitation chamber external surface.

73. The cavitation system of claim 70, said attaching means further comprising an epoxy bond j oint.

74. The cavitation system of claim 70, said attaching means further comprising a braze j oint.

75. The cavitation system of claim 70, said attaching means further comprising a weld joint.

76. The cavitation system of claim 70, said attaching means further comprising a diffusion bond j oint.

77. The cavitation system of claim 59, further comprising a void filling material interposed between at least two adjacent contact surfaces of said acoustic driver assembly.

78. The cavitation system of claim 59, further comprising a void filling material interposed between said second surface of said head mass and said spherical cavitation chamber external surface