U.S. patent number 3,569,751 [Application Number 04/688,112] was granted by the patent office on 1971-03-09 for high voltage generator.
This patent grant is currently assigned to Litton Systems, Inc.. Invention is credited to Lothar H. Ruhnke.
United States Patent |
3,569,751 |
Ruhnke |
March 9, 1971 |
HIGH VOLTAGE GENERATOR
Abstract
An ionized, dielectric fluid flows into a series of ion
transport passageways which extend adjacent to each other and which
taper outwardly in the direction of fluid flow. The passageways are
fabricated from material which is slightly electrically conductive
to preclude charge build up on the passageway walls. Ions arriving
at the high voltage electrode are collected by collector without
the use of an external power supply. The collector has a large
surface area relative to an emitter electrode so that an electric
field is developed between the collector and the emitter electrode
for producing ions of the opposite sign in the fluid. The
oppositely ionized fluid flows into the next passageway where the
ion collection process is repeated. A high potential which builds
up on the emitter electrode renders the device useful as a high
voltage generator.
Inventors: |
Ruhnke; Lothar H. (Honolulu,
HI) |
Assignee: |
Litton Systems, Inc. (Beverly
Hills, CA)
|
Family
ID: |
24763170 |
Appl.
No.: |
04/688,112 |
Filed: |
December 5, 1967 |
Current U.S.
Class: |
310/10; 96/66;
96/77 |
Current CPC
Class: |
H02N
3/00 (20130101) |
Current International
Class: |
H02N
3/00 (20060101); H02n 003/00 () |
Field of
Search: |
;310/5,6,10,11
;103/1 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Sliney; D. X.
Claims
I claim:
1. In a high voltage generator in which ionizer means charges a
charge transport fluid and wherein electrode means collects the
charge from said charged fluid for generating the high voltage, the
improvement which comprises:
housing means defining a passageway for guiding said charge
transport fluid from said ionizer means to said electrode means, at
least one wall of said passageway being fabricated from relatively
conductive, electrically insulating material having an electrical
resistance sufficiently low to effectively remove excess charges
deposited on its surface from the transport fluid and at the same
time sufficiently high as not to remove more than a fraction of the
electrical current delivered to the high voltage electrode; and
conductive means in electrical contact with at least a portion of
said wall opposite said passageway, said conductive means being
adapted to remove said excess charges through said material.
2. A high voltage generator according to claim 1, in which said
material is taken from the group consisting of paper phenolic,
linen phenolic and carbon-filled epoxy.
3. A high voltage generator in accordance with claim 1 in which
said material also has an electric resistivity in the range of
10.sup.-10 to 10.sup.-12 ohm centimeters.
4. A high voltage generator in accordance with claim 1 in
which:
pairs of ionizer means and collector means are arranged in
seriatim;
one of said passageways is provided between said ionizer means and
said collector means of each said pair, said housing means being
constructed with a partition to provide said passageways adjacent
to each other and arranged to guide said fluid in generally
parallel paths; and
said housing means and said partition being constructed to taper
the wall of each of said passageway so that the volume per unit
length enclosed by each said passageway increases in the direction
of fluid flow.
5. A high voltage generator in accordance with claim 1 in which at
least a portion of said partition providing said adjacent
passageways is fabricated from a slightly electrically conductive
material having an electric resistivity in the range of 10.sup.-10
to 10.sup.-12 ohm centimeters so that charges of opposite sign
collected on opposite sides of said partition are neutralized to
preclude the buildup of a high potential on the walls of said
passageway.
6. A high voltage generator operating under the principle that an
insulating fluid passing through a generally parallel, electric
field produced by a with sections element will assume a charge of a
given sign, which comprises:
conduit means having passageways for guiding said fluid along
multiple flow paths wherein said flow paths are generally parallel,
said conduit means being provided with sections interconnecting
said flow paths, each of said sections having an entrance port and
an exit port;
ionizer means for producing ions of said given sign in said fluid
in a first of said flow paths;
means for pumping said insulating fluid through said passageways
and said sections;
conductive means received in each of said sections, said conductive
means having a given surface area exposed to said fluid for
collecting said ions from said fluid;
output electrode means received in each of said sections, said
electrode means being electrically insulated from said conductive
means, said electrode means having a sharp element and a small
surface area exposed to the fluid relative to said given surface
area so that said output electrode means collects fewer ions from
said fluid than said conductive means, said output electrode means
assuming a charge that is substantially less than the charge on
said conductive means; and
a plate electrode electrically connected to each of said conductive
means, each said plate electrode having an opening therein adjacent
to said sharp edge of one of said output electrode means for
inducing an electric field between said sharp element and said
plate electrode and for directing the flow of said fluid through
said field to produce ions in said fluid having a sign opposite to
said given sign.
7. A high voltage generator which comprises:
conduit means having a passageway therein for defining a flow path
wherein adjacent first and second sections of said passageway are
generally parallel;
means for pumping an insulating fluid through said conduit
means;
ionizer means received in a first of said sections for producing
ions having a given sign in said fluid flowing through said first
section;
means interposed between said first section and said second section
of said passageway for collecting said ions from said fluid, said
collecting means including a flat electrode having a slot therein
for directing said fluid into said second section; and
a high voltage output electrode having a first sharp element
positioned adjacent to said slot, said output electrode being
effective to collect fewer ions than said collecting means so that
an electric field is impressed across said flat electrode and said
output electrode to produce ions of a sign opposite to said given
sign in said fluid entering said second section.
8. A high voltage generator according to claim 7, wherein:
said fluid flows in opposite directions in said adjacent first and
second sections; and
at least one wall of said first and second sections is tapered to
provide a cross section area in each passageway which increases in
the direction of fluid flow, said taper of said sections being
effective to maintain in said passageway a relatively constant ion
content per unit length of said passageway.
9. A high voltage generator in accordance with claim 7,
wherein:
said passageway is tortious for forming a plurality of each of said
first and second sections;
second means are mounted between successive ones of said second and
first sections for collecting said opposite polarity ions from each
of said second sections, said second means including a second flat
electrode having a second slot therein for directing said fluid
into the next successive first section;
a first emitter electrode having a second sharp element is mounted
adjacent to said second slot, said first emitter electrode being
effective to collect fewer ions than said second collector means so
that an electric field is impressed across said flat electrode and
said first emitter electrode to produce ions of said given sign in
said fluid entering said next successive first section;
said ionizer means includes a power supply, a second emitter
electrode having a third sharp element and being electrically
connected to said first emitter electrode, and a third flat
electrode having a slot therein adjacent to said third sharp
element, said third flat electrode being electrically connected to
said second collecting means; and
switch means for selectively connecting said power supply to said
third flat electrode to initiate ionization of said fluid, said
switch means being open subsequent to the initial operation of said
apparatus to permit operation of said generator independently of
said power supply.
10. A high voltage generator in accordance with claim 7, which
further comprises a pair of high voltage generators in accordance
with claim 8, the high voltage output electrodes of said pair of
generators being connected in parallel to provide high output
current characteristics.
11. A high voltage generator in accordance with claim 7, which
further comprises a pair of high voltage generators in accordance
with claim 8, the high voltage output electrodes of said pair of
generators being connected in series to provide higher voltage
output characteristics.
12. A high voltage generator which comprises:
housing means defining a passageway for insulating fluid, said
passageway comprising a series of counterflow units, each
counterflow unit comprising a first diverging channel for
conducting said fluid in a first direction and a second diverging
channel generally parallel to said first channel for conducting
said fluid in a second direction opposite to said first
direction;
means for pumping said fluid through said passageway;
a first electrically conductive insert which includes; a first flat
electrode section having a first slot therein to permit passage of
said fluid from said pumping means into said first channel of a
first of said units and a first generally U-shaped section having
one end thereof open for receiving said fluid from each said second
channel of said units and having a second flat electrode at the
other end thereof, said second flat electrode section having a
second slot therein to permit the flow of fluid into the first
channel of the next successive counterflow unit, and a plurality of
electrically interconnected emitter electrodes having a sharp edges
thereon, one of said electrodes being mounted adjacent to said slot
of each said second flat electrodes, said emitter electrodes being
electrically insulated from said first insert; a high voltage power
supply; switch means for selectively connecting said power supply
to said first insert to produce in said fluid ions of a given
sign;
a second electrically conductive insert which includes; a second
generally U-shaped section for each of said units, each said second
section having an opening at one end for receiving said fluid from
said first channels of said units;
a third flat electrode closing the other end of each of said second
U-shaped sections, each said third flat electrode having a third
slot therein to permit the flow of fluid into said second channels
of each of said units; and
a high voltage output electrode for each of said third flat
electrodes, each output electrode being electrically insulated from
said first and second inserts, each of said output electrodes
having a sharp element thereon mounted adjacent to one of said
third slots of said third flat electrodes;
the area of said second section in contact with said fluid having
said given sign being substantially greater than the area of said
output electrodes in contact with said corresponding fluid so that
an electric field is produced across said output electrodes and
said third flat electrodes to produce ions in said fluid in said
second channels of a sign opposite to said given sign;
the area of said first U-shaped section in contact with said fluid
having said sign opposite to said given sign being substantially
greater than the area of said emitter electrode so that upon
disconnection of said power supply from said emitter electrodes an
electrical field is produced across said emitter electrodes and
said second flat electrode sections to produce ions of said given
sign in said fluid in said first channels of said units.
13. A high voltage generator according to claim 12, in which:
each of said first diverging channels is provided with an entrance
port which conforms to said first slot and an exit port which
conforms to said open end of said first U-shaped section; and
said flat electrodes being mounted substantially perpendicular to
said direction of fluid flow through said respective first and
second channels.
Description
BACKGROUND OF THE INVENTION
This invention relates to a high voltage generator and more
particularly, to a self-exciting, high voltage generator utilizing
a highly insulating fluid flowing through a tortuous series of
tapered, ion transport passageways and a series of improved
ionizers. The highly insulating fluid is used as a means of
transporting ions of a given sign to, and ions of an opposite sign
from, an output electrode which is raised to a high potential
during the operation of the generator. The improved ionizers
produce the ions which are transported utilizing the principle that
a fluid passing through a strong electric field generated by a
sharp point or edge will be ionized and will acquire a charge of
the same sign as the potential of the sharp edge or point relative
to a nearby conducting surface.
In the past, various high voltage generators have been suggested.
Charge transport fluids in such generators have been aerosol,
gaseous and liquid. Extensive analysis, experimentation and
investigation into such prior high voltage generators indicates
that the foregoing principle may be used for high voltage
generation. Applicant's research has indicated, however, that such
prior high voltage generators have not achieved commercial
acceptance because certain basic factors in high voltage generator
design have been overlooked. As an example, it has been found that
the efficiency of such generators is limited by the existence of an
unneutralized electric field caused by the presence of a large
number of ions of a given polarity flowing along the channel. This
field forces many of the ions from the stream thereby reducing the
total current delivered. Hence, the output current of such prior
high voltage generators is limited. It is known that the output
current of such high voltage generators is determined by the fluid
flow rate and the space charge density in the ion transport
passageway. In a single stage of such a high voltage generator, it
is not possible to generate infinitely high output current because
the space charge density in the ion transport passageway is limited
by the electric field it generates, the geometry of the ion
transport passageway, the breakdown properties of the fluid, and
the flow rate of the fluid. Further, the flow rate of the fluid is
limited because its charge carrying capacity diminishes when
cavitation develops and tends to produce arcing across the
electrodes of the ionizer. On the other hand, the fluid flow rate
cannot be too low because a minimum rate is required to flush out
of the ionizer a desired percentage of ions which are produced.
A critical consideration in the operation of such a high voltage
generator is the operating efficiency. Considering a typical
desired electrical output of 1,000,000 volts in a generator
operating at a space charge density (q) of 0.07 coulombs per cubic
meter, then the electrical pressure would be 10 p.s.i. This means
that for an efficiency of 50 percent, the mechanical pressure drop
must be limited to 10 p.s.i., which is a relatively low pressure
drop. The allowable mechanical pressure drop becomes important when
the fluid is liquid and when one attempts to provide a fluid pump
which operates against relatively low pressures at the flow rates
required. The characteristics of available liquid pumps generally
make it advantageous to cascade the fluid flow paths which has led
to electrical breakdown and generator size problems in the
past.
In the operation of such prior high voltage generators, while a
high electric field is being produced in the direction of the ion
transport passageway, a radial electric field is produced by the
space charge in the passageway which tends to dissipate the ions
radially. Such prior generators have used ion transport passageways
fabricated from electrical insulators having very high insulating
characteristics. Because of the radial field, ions move toward the
walls of the passageway and, as a result of the high insulating
characteristics of the passageway material, no appreciable current
flows through the walls, hence, a charge builds upon the walls.
Because of the lack of current flow through the walls, the charge
which builds up on the walls soon exceeds the voltage at which wall
breakdown and sparking occur. Sparks may follow a path along the
wall in a direction parallel to the longitudinal field or may tend
to move radially across the wall. In either case, sparks deposit on
the wall a thin conductive film, such as carbon if the wall is
plastic, which film provides an easier path for arcing upon the
occasion of the next breakdown. As more breakdowns occur, the
conductive deposit builds up and produces a short circuit path from
the ion collector to ground or a short circuit through the wall to
ground or to an adjacent fluid channel. In either situation, the
walls are permanently damaged and must be replaced.
In an attempt to reduce the space charge density in the ion
transport passageway and to lessen the charge buildup and breakdown
problems, it has been suggested to use relatively wide ion
transport passageways. However, overall efficiency is reduced
significantly in this manner because the fluid volume flow rate
must be increased to carry the same number of ions to the ion
collector.
Another limitation in such prior high voltage generators which
relates to the high longitudinal electric field has been the
relatively low breakdown voltage between the ion collector and the
collector electrode of the ionizer. Such low breakdown voltages
result from the configurations of the electrodes in the ionizer
which in the past have provided many relatively sharp metal
elements at which the electric field concentrates. For example, in
high voltage generators in which a charged aerosol is fed through a
tube into an ion transport passageway, the tube provides a
relatively sharp location at which the electric field lines
concentrate. The concentrated electric field lines reduce the
breakdown voltage between the tube and an ion collector, hence, the
maximum voltage which the generator can generate is limited.
Further, in other high voltage generators, large apertures, such as
those formed by annular rings, are used as collector electrodes in
conjunction with pointed emitter electrodes. In such case, the
electric field concentrates at the ring and substantially reduces
the breakdown voltage. Applicant's extensive investigation and
experimentation indicates that the collector electrode of the
ionizer should be in the form of a relatively small cavity
containing a flat plate positioned more or less perpendicular to
the fluid flow path so that it blocks the flow path, except for a
small opening to permit the escape of fluid at high velocity.
Further, in prior high voltage generators, it has been customary to
use ion collectors having large surface areas for collecting the
ions transported through the ion transport passageway. The
operating principle of such collectors is based upon the fact that
if an ionized fluid remains in a container long enough Coulomb
forces will cause the ions to diffuse or move to the surfaces of
the ion collector. However, for this type of operation, applicants
have found that the collector volume must be of the order of 1
cubic meter per milliampere of output current produced. Thus, for a
high voltage generator having an output of 10 milliamperes, one
would need a 10 cubic meter volume just for the ion collector. At a
specific gravity of .89 of a suitable liquid carrier fluid, such as
transformer oil, the collector would contain 19,580 pounds of
fluid, which is clearly a prohibitive weight.
SUMMARY OF THE INVENTION
Research involving a careful study of the problems associated with
such prior high voltage generators indicates that such problems can
be eliminated or reduced to insignificant proportions by a device
constructed according to the principles of the present invention. A
plurality of ion transport passageways are used wherein adjacent
passageways transport fluid flowing in opposite directions and
carrying ions of opposite sign. This results in the elimination of
the overall electric field produced by the net space charge and
greatly reduces the diffusion of ions to the walls of the
passageways. Reduction of ion diffusion to the walls also tends to
reduce the danger of internal arcing. This difficulty is further
reduced when the ion transport passageways are fabricated from a
slightly conductive, electrically insulating material. Rather than
forming high potential differentials on opposite sides of a highly
insulating wall, the slightly electrically conductive insulators
conduct a small current. The conduction is sufficiently small that
it does not cause a serious loss of output current while it
prevents breakdown along or through the walls of the fluid
passageway so that should the output voltage be uncontrolled,
ultimate breakdown occurs in the fluid. Such breakdown in the fluid
is more desirable because it does not produce a conductive deposit
on the walls and does not lead to destruction of the walls.
Further, in another embodiment of applicant's invention, an
improved high voltage generator may include ion transport
passageways having cross-sectional areas which increase with
increased distance along the fluid flow path. This achieves:
1. a near zero overall space charge density even though the space
charge decreases as the ionized fluid flows down an individual
channel, and
2. a diffuser section providing a reduced fluid velocity and larger
cross section area to decrease the pressure drop per unit travel
distance in the liquid prior to passage of the liquid through a
subsequent ionizer.
In one embodiment of the present invention, the functions of
collecting ions of a given sign and producing ions of a sign
opposite to the given sign are performed by an improved ionizer
which uses an ion collector which is small relative to those used
in prior high voltage generators. The ion collector is located at
the downstream end of an ion transport passageway and collects a
portion of the incoming ions from the fluid. The fluid passes
through a slot in a flat plate electrode section of the ion
collector and into the next passageway. The number of ions
collected by the collector greatly exceeds the number collected by
an emitter electrode having one or more sharp points or edges
positioned adjacent to the slot so that an electric field is
developed in the space between the sharp edge and the flat plate
electrode. The electric field produces ions of a sign opposite to
the sign of the ions which were collected by the collector. Ions of
opposite signs combine and the excess ions of the opposite sign to
that flowing into the collector will flow with the fluid through
the next passageway and will complete the collection by
neutralization of the remainder of the incoming ions.
An object of the present invention resides in a new and improved
high voltage generator.
Another object of the present invention is to provide a high
voltage generator in which spark erosion of passageways for guiding
dielectric fluid is eliminated.
Still another object of the present invention resides in the
provision of ion transport passageways which are tapered to provide
the same ion density per unit length of the passageways.
Yet another object of the present invention is to provide an ion
collector and fluid ionizer which is effective to reverse the
polarity of ionization of a dielectric fluid while generating a
high voltage without the use of an insulated power supply in the
high voltage area.
DESCRIPTION OF THE DRAWINGS
Other objects and advantages of the present invention will become
apparent from the following detailed description when considered
with the accompanying drawings in which:
FIG. 1 is an elevational view taken in cross section of the high
voltage generator of the present invention illustrating a plurality
of generally parallel, tapered ion transport passageways spaced by
ion collectors where a high potential is developed;
FIG. 2 is a cross-sectional view taken along line 2-2 in FIG. 1
showing emitter electrodes which are connected to a high voltage
output terminal;
FIG. 3 is a schematic view illustrating a number of the high
voltage generators of the present invention connected in series;
and
FIG. 4 is a schematic view showing a plurality of the high voltage
generators of the present invention connected in parallel.
DESCRIPTION OF THE DISCLOSED EMBODIMENT
Referring now in general to the drawings, there is shown in FIG. 1
an improved high voltage generator 10 constructed according to the
principles of the present invention. The advantageous features of
the high voltage generator 10 may be illustrated with any of the
commonly used working fluids such as insulating or dielectric
liquids, gases and aerosol laden gases. The actual choice of an ion
transport fluid for the generator 10 will result from
considerations such as voltage range to be produced, current
requirement, type of power available, etc. For purposes of
illustration, the fluid described herein will be a dielectric or
insulating liquid.
The generator 10 includes a motor 12 for driving a pump 14 which
forces a dielectric liquid 16 into a high voltage generator section
18. In the generator section 18, the liquid 16 is subjected to a
strong electric field in an ionizer 20 where ions of a given sign
(such as negative) are produced in the liquid 16. The ions flow
with the liquid 16 into a conduit such as a tapered ion transport
passageway 22 and form a space charge which advances to an ion
collector 24. A high voltage output or emitter electrode 26 at the
ion collector 24 is designed to collect significantly fewer ions
than that collected by the ion collector 24 and becomes positively
charged relative to the charge on the ion collector 24 and that on
a flat plate electrode 28 which is provided with a narrow slot 30
and which is electrically connected to the ion collector 24.
The relative charge on the emitter electrode 26 and the ion
collector 24 induces an electric field therebetween, which produces
ions having an opposite (such as positive) sign from that of the
given sign. The negative ions which are not collected are
neutralized by the positive ions and the excess positive ions are
urged by the flow of the liquid 16 into the next ion transport
passageway 32. A high voltage output terminal 34 is connected to
the emitter 26. The ionization, ion collection and ionization
process is repeated as the liquid 16 flows through the tortuous
path formed by the series of ion transport passageways 22, 32,
etc., so that a high voltage, such as more than 500,000 volts, is
applied to the output terminal 34. It is observed that the
ionization is achieved by the electrodes 26 and 28 without the
connection thereof to an independent power supply.
Considering FIGS. 1 and 2 in detail, the pump 14 may be a
centrifugal type pump capable of operation at a range of 10 to 100
p.s.i. at liquid flow rates of 10 to 500 gpm, depending upon the
pressure drop across the generator section 18 and the desired
liquid flow rates in the ionizers. The pump 14 forces the liquid 16
into an input conduit 42 which is connected to an input port 44 of
the generator section 18. The generator section 18 is fabricated
from electrically insulating material which is slightly
electrically conductive at the electric potentials which exist in
the ion transport passageways. The materials paper phenolic, linen
phenolic, slightly electrically conductive carbon filled epoxy
material, and a material sold under the trade name "Benelex 70" by
the Masonite Company, have been used successfully. These materials
have resistivity in the range of 10.sup.-10 to 10.sup.-12 ohm cm.
The materials have been suitable for use, for example, when
transformer oil is used as the liquid 16. These materials provide a
low leakage current flow to a metal shield 46 surrounding the
generator section 18. Such flow prevents a high charge from
building up on the walls 38 of the ion transport passageway 22 as a
result of ion diffusion to the walls. When such a charge builds up,
breakdown occurs relatively easily along the walls 38 and
significantly reduces the breakdown voltage between the collector
24 and the ionizer 20. With the slightly conductive material, the
breakdown voltage is limited only by that of the dielectric liquid
16. Thus, the generator section 18 may be fabricated from such
materials having a resistance which is low enough to remove excess
charges deposited on the passageway surfaces and at the same time a
resistance which is high enough as not to remove more than a
fraction, such as 5--10 percent of the current which is delivered
to the electrode 34.
More particularly, the slightly electrically conductive material is
effective to insulate against electrical breakdown through or along
the walls 38 of the ion transport passageway 22 which enclose the
space charge formed by the ions moving toward the ion collector 24.
In the design of the generator section 18, the space charge density
(q), the ion mobility (b) and the breakdown potential (E.sub.b-f)
are primary design factors which are known once such factors as
liquid flow rate and the specific liquid 16 are determined. Thus, a
breakdown factor (F.sub.b), where F.sub.b = (E.sub.b-f) .sup.. (q)
.sup.. (b), is known. Applicants have determined the breakdown
factor (F.sub.b) must be less than or equal to an insulating factor
(F.sub.I) of the material used to fabricate the walls 38. The
insulating factor (F.sub.I) is equal to the product of the
electrical breakdown potential (E.sub.b-i) of the insulating
material and the conductivity of the material (c). When this is the
case, the slightly electrically conductive material will conduct
current at an electrical potential which is lower than the
breakdown potential of such material. Thus, the ions which diffuse
to the walls 38 will be ineffective to build up a potential
sufficient to cause breakdown along or through the walls 38.
Rather, the only breakdown which will occur should the voltage not
be controlled will be in the fluid 16, which is not destructive to
the walls 38.
The liquid 16 for this design has a viscosity in the range of .8 to
1.2 poise. It has been found that transformer oil, such as sold as
Type 10c by the General Electric Company, is as satisfactory for
use as the dielectric liquid 16. With such a relatively high
viscosity, the space current which can be delivered at the end of
the ion transport tube 22 away from the ionizer 20 may be as high
as 80 percent of the initial space charge density at the entrance
to the ion transport passageway 22.
The ionizer 20 is provided in a generally rectangular cross section
portion 52 of the inlet port 44. The ionizer 20 includes an emitter
electrode 54 which may be in the form of a point or points, and
which is shown in the drawings in the general configuration of an
injector razor blade. The emitter electrode 54 is mounted on a
conductive support 56 which is secured to a wall 58 of the portion
52. The support 56 is electrically connected to an electrical
conduit such as a wire 60 connected to ground. The emitter
electrode operates in conjunction with a flat collector electrode
62 which may be in the form of a flat plate 64 provided with a
suitable slot 66 and an aperture 68 to permit passage of the liquid
16 therethrough. By providing narrow slots in the plate opposite to
elongated, bladelike emitter electrodes, applicants do not provide
any locations at which the electric field tends to concentrate. In
this manner, applicants avoid serious reduction in the breakdown
voltage and do not limit the voltage which can be built up at the
ion collector.
In a specific embodiment of the ionizer 20, the emitter electrode
54 may be fabricated from an injector-type razor blade, such as a
stainless steel, single-edge injector-type razor blade sold by the
Schick Company. Such a blade has a length in the direction of fluid
flow (as viewed in FIG. 1) of 8 mm., a width of 37 mm., and a
thickness of .26 mm. In such embodiment, the flat collector
electrode 62 is provided with a slot 66 which is opposite to the
tip 78. The slot may provide a 1 mm. by 37 mm. opening through
which the fluid 16 may pass. The tip 78 is located .8 -- 1.2 mm.
away from the side of the collector electrode 62 nearest the
emitter electrode 54.
The collector electrode 62 is connected to a conductor 72 which is
connected to a power supply 74 across a current limiting resistor
76 and a control switch 77. The power supply 74 provides a high
voltage, such as 15--20 kV across the emitter and collector
electrodes 54 and 62, respectively, for establishing a very high
electric field adjacent to the tip 78 of the emitter electrode. As
the liquid 16 flows past the emitter electrode 54, the high
electric field ionizes the liquid and produces negative ions, for
example, so that a space charge is developed. The pump 14 is
adjusted to provide a given liquid flow velocity, such as 20 meters
per second, through the slot 66. The ions attempt to flow to the
collector electrode 62, but with the given flow velocity through
the slot, sufficient ions are flushed into the ion transport
passageway 22 to develop an initial space charge density of 0.1
coulombs per cubic meter, for example, in the passageway. Under
conditions such as these, less than a 1.0 microampere current flows
from the tip 78 to the collector 62, thus, the power supply 74 need
only supply a low output current and relatively low electrical
input into the generator 10.
The space charge flushed into the ion transport passageway 22 is
advanced by the flowing liquid 16 into the ion collector 24. In the
embodiment shown in FIGS. 1 and 2, the ion transport passageway 22
is provided with a generally rectangular cross section which
commences adjacent to the slot 66 in the flat electrode 62. The
passageway 22 defines a channel or flow path for the liquid 16. The
opposite walls 38 of the passageway 22 taper outwardly, whereas
sidewalls 82 (FIG. 2) thereof are parallel. Clearly, tapering walls
of the passageway 22 can be provided by other cross-sectional
configurations to compensate for the fact that the space charge
density decreases as the downstream distance from the ionizer 20
toward the ion collector 24 increases. In this manner, the net
space charge in any given cross section of the passageway 22 is
approximately the same as the net space charge in an adjacent cross
section of the adjacent passageway 32. Accordingly, there is
essentially no net radial field transverse to the direction of the
fluid flow in the passageways 22 and 32. In addition, the tapering
of the walls 38 provides a diffuser section which reduces the
pressure drop as the liquid flows in the passageway 22 to provide a
concentration of pressure drop where the liquid enters the ion
collector 24.
The ions which are lost as the space charge advances to the ion
collector 24 advance to the walls 38 of the passageway 22. Because
the walls are slightly conductive, a charge does not build up on
the walls. Rather, a small current is conducted therethrough to the
metal shield 46 so that no breakdown of the walls 38 occurs. In
this manner, the voltage developed across the length of passageway
22, for example, will be limited only by the voltage that will
cause the liquid 16 to break down.
The ions which are not lost during the transit in the ion transport
passageway 22 to the ion collector 24, pass through an aperture 82
in the flat plate electrode 28 and enter the ion collector 24. The
ion collector 24 can be fabricated from separate parts or can be
made in one unit as a single insert, for example. The ion collector
24 includes the metal, flat plate electrode 28 which is connected
to a metal collector 84 having a plurality of sections 85 provided
with generally semicircular cross sections and extending along the
same width as the passageway 22. A metal portion 86 is provided on
the flat electrode 28 within each section 85 for guiding the flow
of the liquid 16 from a generally upward direction as it flows
through the aperture 82 to a generally downward direction (as
viewed in FIG. 1) where the liquid passes the emitter electrode 26
and then flows through the slot 30 in the electrode 28. The metal
collector 84, including the portion 86 and electrode 28, are
electrically interconnected and are insulated from the emitter
electrode 26 and the remainder of the generator by the slightly
electrically conductive material which forms the housing of the
generator section 18. The emitter electrode 26 may have the same
detailed construction as the emitter electrode 62 of the ionizer
20. Similarly, the spacing of the electrode 28 and the dimensions
of the slot 30 thereof may be the same as in the ionizer 20. By
making the emitter electrode 26 of small area and size, the
internal electrical capacitance of the generator unit 10 is
small.
In the operation of the ion collector 24, the ions entering the
aperture 82 diffuse onto the surfaces of the collector 84, the
portion 86 and the flat electrode 28 which are exposed to the
liquid 16. For ease of description, the surfaces of these elements
84, 86 and 28 which are exposed to the liquid 16 will be referred
to as the main ion collector surfaces, whereas the surfaces of the
emitter electrode 26 which are exposed to the liquid 16 will be
referred to as secondary ion collector surfaces. Because the main
ion collector surfaces have many times more area than the secondary
ion collector surfaces, the main surfaces collect ions at a much
higher rate than the secondary surfaces. If the ions entering the
ion collector 24 are negatively charged, then the secondary
surfaces will be charged less negatively, hence positively relative
to the high negative charge on the main surfaces. As the difference
in the charge on the main and secondary surfaces increases, a high
electric field is developed so that the fluid in a volume 98
adjacent to the tip 96 is ionized to create a space charge having
opposite (positive) sign with respect to that of the space charge
in the passageway 22. The space charge is flushed out of the volume
98 of the ion collector 24 and into the next subsequent ion
transport passageway 32 where the operation described above with
respect to the passageway 22 is repeated. The adjacent passageways
22 and 32 form counterflow paths for the liquid 16 and for purposes
of description, can be considered as one counterflow unit.
In the operation of the ion collector 24, the rate of diffusion of
negative ions to the main ion collector surfaces is in equilibrium
with the rate at which the positive ions are conducted from the tip
96 to the flat electrode 28. Accordingly, the voltage on the main
ion collector surfaces with respect to the tip 96 will stay
constant, and the number of negative ions collected by the main ion
collector surfaces is proportional to the number of space charges
entering the aperture 82 and the percent of positive ions flowing
through the slot 30.
The walls 102 of the passageway 32 are tapered and diverge with
increasing distance from the plate electrode 28 to the aperture 68
in the electrode 62. This tapering provides a constant number of
ions per unit of length of the passageway even though the space
charge density decreases with fluid flow away from the electrode
28. The main ion collector surfaces and secondary ion collector
surfaces are proportioned so that approximately the same space
charge density is developed at the start of the passageway 32 as is
developed at the start of the passageway 22. Thus, at adjacent
cross sections of the passageways 22 and 32, the net radial field
will be near zero.
As shown in FIG. 1, an ion collector 112 similar to the ion
collector 24 is provided at the end of the passageway 32 for
collecting the positive ions which pass through the electrode 68
and negatively ionizing the fluid 16 which enters a next subsequent
ion transport passageway 114. The cycle of collecting ions and
reionizing the liquid 16 is repeated as the liquid flows through
successive ion transport passageways 116, 118, and 120 and sections
85 and 122 of the ion collectors 24 and 112, respectively. The
liquid 16 may be neutralized by an ionizer (not shown) provided at
the end of the passageway 120 prior to entrance into a return
conduit 124 which supplies the liquid 16 to the pump 14.
The high voltage generator 10 may be operated independently of any
external power source by opening the switch 77 after initial
operation so that the power supply 74 is not connected to the
electrode 62. In this independent mode of operation, the electrode
62 attains a floating potential as hereinafter described. The
electrode 62 of the ionizer 20 is maintained at a positive
potential (relative to the electrode 54) by the power supply 74 so
that negative ions are generated and flow through the slot 66 into
the ion transport passageway 22. The negative ions are collected
and positive ions are formed in the ion collector 24. The positive
ions are flushed into the passageway 32 and are collected on main
ion collector surfaces 113 of the ion collector 112. The potential
on the surface 113 of the collector 112 rises until it reaches
approximately the same potential as is applied by the power supply
to the electrode 62. Because the ion collector 112 is electrically
connected to the electrode 62, the power supply 74 can be
disconnected by opening the switch 77 to initiate the independent
mode of operation.
The supply of positive ions to the surfaces 113 of the ion
collector 112 is maintained as a result of current flow to the
terminal 34. If the terminal 34 is open, for example, the high
voltage on the terminal 34 will induce a displacement current to
the terminal 34. The displacement current will be conducted to the
electrode 26 to permit generation of positive ions which are
flushed into the passageway 32 for collection on the surface 113 of
the ion collector 112. The positive ions will maintain the
electrode 62 at the potential required to negatively ionize the
fluid 16 flowing into the passageway 22 and maintains a high
relative potential across an emitter electrode 115 of the ion
collector 112 to permit negative ionization of the fluid entering
the passageway 114.
The generator 10 provides a high negative voltage at the high
voltage terminal 34 by initially imposing a negative potential on
the emitter electrode 54 in the ionizer 20. The generator 10 will
perform equally well as a generator of a high positive voltage by
impressing a positive potential on the emitter electrode 54 instead
of the negative potential.
Referring now to FIG. 3, a number of generator units are shown
having the high voltage output terminals 34 thereof connected in
parallel to a high voltage power line 140 which is connected to a
load 150. In this manner, the generators 10 of the present
invention may be used to provide higher current capacity than that
available from one generator.
Referring to FIG. 4, there is shown a number of generator units 10
having the high voltage terminals thereof connected in series with
a load 151. Stabilizing loads 152 are connected to the terminals
34.
It is to be understood that the above-described arrangements are
simply illustrative of the application of the principles of this
invention. Numerous other arrangements may be readily devised by
those skilled in the art which will embody the principles of the
invention and fall within the spirit and scope thereof.
* * * * *