US2928942A - Ion generator - Google Patents

Description

March 15, 1960 w, w, H|Ks ETAL 2,928,942

10N GENERATOR Filed Feb. 15, 1957 2 Sheets-Sheet 1 1:*-1E1 J f #335 3 ATTORNE Y.;

March l5, 1960 Filed Feb. 15.` 1957 W. W. HICKS ETAL ION GENERATOR 2 Sheets-Sheet 2 F'IE E v 1.4 TTOR/VE YJ' United States Patent N GENERATOR William Wesley Hicks, Sau Francisco, and John C. Beckett, Kent'ield, Calif., assignors to Ionaire, Inc., San Francisco, Calif., a corporation of California Application February 15, 1957, Serial No. 640,434 11 Claims. (cl. 2504-44) r[his invention relates generally to a method and apparatus for generating ions and more particularly to a method and apparatus for generating ions in a safe and economical manner.

it is weil known that when radioactive sources are used for ion generation, additonal means is ofteny provided for collecting the undesired ions. Means also must be provided in conjunction with the ion generator-to prevent shock and to prevent contamination from the radioactive source. Heretofore, the means utilized for accomplishing such protection has been relatively expensive and unduly bulky. l

In general, it is an object of the present invention to provide an improved method and apparatus for generating ions.

Another' object of the invention is to provide ion generating apparatus with particularly novel means for preventing shock and for preventing contamination from the radioactive source utilized therein.

Another object of the invention is to provide apparatus of the above character in which the protective means does not unduly interfere withthe production of the desired ions.

Another object of the invention is to provide apparatus of the above character in which particularly novel means is utilized for collecting the undesired ions.

Another object of the invention is to provide apparatus of the above character inwhich novel means is utilized for indicating the dangerous area of the apparatus.

Additional objects and features of the invention will appear from the following description in which the preferred embodiment has been set forth in detail in conjunction with the accompanying drawing.

Referring to the drawing:

Figure l is a side elevational view of an ion generator incorporating the present invention.

Figure 2 is a front elevational view of the holder.

Figure 3 is a cross sectional view taken along the line 3-3 of Figure 2.

Figure 4 is a cross sectional view taken along the line 4-4 of Figure 3. Y

Figure 5 is a view of a piece of tritium foil.

Figure 6 is a view schematically illustrating a portion of the ion generator together with the electrical circuitry therefor.

Figure 7 is a front elevational view showing the ion generator mounted in a conventional air conditioning unit.

Figure 8 is a cross sectional view taken along the line 8 3 of Figure 7.

in general, the present invention employs a radioactive source which emits soft beta particles. particles ionize the air in a region adjacent the radioactive source. A collecting electrode is mounted adjacent the radioactive source and is provided with a charge of the sign opposite the sign of the undesired ions. The electrode collects the undesired ions and repels the de-A The soft beta,

A.l CC

sired ions into the surrounding air. A guard is mounted over the radioactive source and the electrode to prevent touching of the radioactive source and the electrode to thereby prevent electrical shock and undesirable contamination. The guard is of such a construction that it docs not unduly inhibit the production of the desired ions. A transparent member coated with a phosphorescent substance is provided to indicate the dangerous Zone.

The embodiment of our invention illustrated in Figures l through 6 or the drawing consists of suitable supporting means such as a stand 11 and a holder 12. The stand 11 is comprised of a base 13 which forms an enclosure for the power supply (hereinafter described) for the ion generator. A hollow iexible member 16 has one end mounted on the base 13 and the vother end connected to a female receptacle l. The power supply 14 is confnected to the female receptacle 18 by a lead (not shown) extending through the tlexible member 16. y y Y The holder 12 is shown in detail in Figures 2 and3 and consists of a mounting member 22 in any ,suitable shape such as circular and a guard member 23 of a similar shape. rFhe members 22 and 23 can be formed of any suitable material preferably transparent such as polystyrene. The mounting member 22 is formed with a raised central portion 24 and an annular raised lip 26 which are adapted to mount a circular disc-like elec;- trode 27 as shown. The disc-like electrode can be formed of any suitable material such as stainless steel.

An insert 28 of suitable amterial such as brass i`s cari ried by the central portion 24 and is provided with acoli lar 29 which is adapted to support the central portion of the disc-like electrode 27. The insert 28 is provided with a lip 31 which extends through a central opening 32 in the disc-like electrode. rEhe lip 31 is spun over the inner margin of the disc-like electrode 27 adjacent the opening 32 to form mechanical and electrical connections between the insert 28 and the disc-like member 27. An electri cal connector 33 of the male banana plug type is shown threaded into the insert 28 and is adapted to be received by the female receptacle 18 as shown particularly in Figure 1.

A suitable radioactive member 36 is provided within the holder 12. In this instance, the radioactive member 36 has been mounted centrally within the holder 12 over the central opening 32 in the disc-like electrode 27. Oii type of radioactive member found to be particularly suitable consists of a piece of tritium foil 1A" square. The tritium foil is of the type manufactured by U.S' Radium Corporation of New York, New York; The tritium foil is cut in square shape because this make possible the most economical use of sheets of tritiui foil. However, as is readily apparent, the shape of the tritium foil is of no particular importance in the present invention. The tritium foil may be of any desired strength. In the present embodiment, we have found it de# sirable to use tritium having a strength of 50-100 millil curies. The tritium foil may be in contact'with the disci like electrode 27. However, it is not necessary that kthe tritium foil be in contact with the electrode 27 for propel ion generation as hereinafter described.

The radioactive member 36 and the disc-like electrode:` 27 are held in place by the guard memberY 23 which li an annular depending portion 38 which is adapted to seat within an annular groove formed between the lip 26 and the outer margin of the mounting member 22'. Suitable means is provided for securing the guard mem# ber 23 to the mounting member 22 and in this case when both members are formed of polystyrene, a suitable plas# tic cement is used.

` As is apparent from the drawing, the guard member 23 is provided with a plurality of radially extending ribs 41 which are inclined to the left as viewed in Figure 3 as the ribs approach the center of the guard member. Near the center of the guard member, the ribs are inclined to the left more sharply and the lower inner margins of the ribs form a circular opening of a diameter substantially the same as the general dimensions of the radioactive member 36.

The guard member 23 is formed with an annular recess 42 which is adjacent the inner margins of the ribs 41. The annular recess 42 accommodates a ring-like member 43 of suitable material such as polystyrene which has the surface adjacent the radioactive member 36 coated with a phosphorescent substance. The size of the recess 42 and the ring-like member 43 is such that the lower surface of the ring-like member 43 is pressed into intimate contact with the radioactive member 36 for a purpose hereinafter described. The ring-like member 43 -is of such a size that it will cover the least possible surface of the radioactive member 36 and at the same time still provide means for holding the radioactive member in position. Thus, as shown particularly in Figures 4 and 5, the ring-like member only engages the corners of the radioactive member. The portions of the corners which are engaged by the ring-like member 43 are shown shaded in Figure 5.

The disc-like electrode 27 is provided with a charge from the power supply 14. A circuit diagram of the power supply is shown in Figure 6. The circuitry in Figure 6 includes current supply lines L1 and L2 which are represented by the power cord 46 in Figure 1. Lines L1 and L2 are connected to the primary of the transformer 47. The secondary of the transformer is `connected to the opposite junctions of a rectiiier 48, one side of the secondary being connected through a series current limiting resistor 49. The positive side of the other pair of opposite junctions is connected to ground whereas the negative side is connected to the electrode in the holder 12. A lamp or pilot light 50 is connected between lines L1 and L2 and serves to indicate when the ion generator is in operation.

The operation of our ion generator shown in Figures 1 through 6 may now be briefly described as follows: Let

it be assumed that current is being supplied to lines L1 and L2 and that the rectifier 48 is supplying a charge of `negative sign to the disc-like electrode 27. Since the other side of the rectifier is grounded to the base 13, an electrostatic field is created between the electrode 27 and the base 13.

The tritium foil which is used as the radioactive member 36 continuously emits a plurality of soft beta particles which causes ionization of the air immediately adjacent the surface of the tritium foil. As soon as the positive and negative ions are formed by ionization of the air, they are separated by the electrostatic eld. Since the electrode 27 carries a negative charge, any positive ions created by ionization of the air in the vicinity of the tritium foil are immediately collected by the electrode 27. The ions of the same sign as the sign of the electrode 27, that is, the negative ions, are repulsed from the electrode and pass into the surrounding air. Ion separation is enhanced because it is carried on in relatively quiet air adjacent the tritium foil.

The construction of the guard member 23 is particularly important in view of the fact that it does not unduly inhibit the production of the desired ions. For this reason, the central area immediately overlying the tritium foil is open to allow the negative ions free access to the surrounding air. The undesired positive ions are readily collected by the disc-like electrode 27 through the spaces between the ribs 41. It will be noted that the area of the disc-like electrode 27 is substantially greater than that of the radioactive member 36. The size of the electrode 27 provides a large surface for the collection of undesired ions and serves to insure that relatively few positive ions escape into the surrounding air. It has been found that when the guard member 23 is formed of a phoresce.

4 material such as plastic, it assumes the same polarity as the electrode 27 and thus facilitates collection of the undesired ions.

The radioactive element 36 may also serve as an electrode for collecting the undesired ions if the radioactive member is formed of suitable material. For example, if the radioactive member is formed of tritium foil it may serve as a collector for undesired ions as disclosed in our co-pending application Serial No. 580,902 filed April 26, 1956. It has, however, been found that the present apparatus will operate satisfactorily even though the radioactive member is spaced a slight distance from the electrode 27 so that it does not carry the same charge as the electrode.

It is readily apparent that the voltage applied to the electrode 27 may be harmful to life and that the radiations from the radioactive member 36 may also be harmful. For this reason the guard member 23 has been placed over the electrode 27 and the radioactive member 36. The ribs 41 serve to prevent bodily contact with the electrode 27. The opening formed by the ribs adjacent the radioactive member 36 is of such a small size that bodily contact with the radioactive member is almost impossible. If tritium foil is used as the radioactive member as herein described, there is very little danger from radioactivity because the tritium foil only emits soft beta particles. However, to prevent any possible contamination from the foil, the guard member 23 is placed over the foil.

In addition to causing ionization of the surrounding air, the radioactive member is utilized for causing the phosphor coating on the ring-like member 43 to phos- However, only the portion of the phosphor coating in intimate contact with the radioactive member 36 will phosphoresce. The phosphoresencc is visible because the ring-like member 43 and the guard member 23 are transparent.

By way of example, one ion generator found to give excellent results had the following characteristics. The holder 12 had a diameter of approximately 2". The electrode 27 had a diameter of approximately 11/2 and as hereinbefore described, the tritium foil was 1A" x 1A square. The electrode 27 was operated at a negative 360 volts. However, it has been found that satisfactory results can be obtained with the voltage on the electrode 27 ranging from 150 volts to 1200 volts.

It is readily apparent that the apparatus hereinbefore described may be utilized for producing positive ions instead of negative ions merely by changing the sign of the voltage on the electrode 27.

In Figures 7 and 8, we have shown the holder 12 mounted in a conventional air conditioning unit 51 having louvers 52 covering the opening through which the conditioned air is discharged. A power supply 63 is mounted Within the air conditioning unit for supplying the holders 12. It will be noted that the holders 12 are mounted with respect to the louvers 52 in such a manner that the forward portion of the holder 12 is flush with the louvers 52 of the air conditioner. This serves to prevent the louvers of the air conditioner from collecting the ions which it is desired to discharge into the surrounding air. Thus as the air is discharged from the conditioning unit, the negative ions discharged from the holder 12 are carried with the air stream.

It will be noted that the holders 12 are positioned so that the guard member 23 faces away from the air ow, and the air flow does not interfere with the separation of the ions. This makes it possible to carry on ion separation in relatively quiet air.

It is apparent from the foregoing that we have provided a new and improved method and apparatus for generating ions of the desired sign.

We claim:

l. In an ion generator, a mounting member, an elecnode carried by said mounting member, a radioactive member overlying said electrode and in a plane parallel to said electrode, said radioactive member causing ionization of the air in the vicinity of the radioactive member to produce a dense plasma of positive and negative ions, means for applying a charge of one sign to said electrode to establish an electrostatic held whereby ions of the sign opposite the charge on the electrode are collected by the electrode and ions of the same sign as the charge on the electrode are repulsed therefrom, and a guard member covering said electrode and said radioactive member to prevent bodily contact with said electrode and said radioactive member, said guard member being formed of a material to prevent disturbance of the electrostatic eld and being formed with a plurality of spaced openings permitting access to said electrode and said radioactive member to permit discharge of the desired ions and collection of the undesired ions. k

2. An ion generator as in claim l wherein said guard member is formed with a plurality of radially extending ribs defining a central opening overlying the radioactive member and a plurality of spaced openings overlying said electrode.

3. An ion generator as in claim 2 together with a phosphor coated member in intimate contact with a portion of said radioactive member, said phosphor coated member being substantially transparent.

4. In an ion generator of the type adapted for use in an air conditioning unit having louvers through which the air is discharged, the outer surfaces of the louvers forming a substantially planar surface, a mounting adapted to be disposed behind the planar surface formed by the louvers, radioactive means carried by the mounting, said radioactive means serving to ionize the air in the vicinity of the same to cause the production of a ldense plasma of positive and negative ions, a collecting electrode carried by said mounting in relatively close proximity to said radioactive means and lying in a plane parallel to the radioactive means, means for applying a charge of one sign to said collecting electrode whereby ions to establish an electrostatic eld of the sign opposite the charge on the electrode are collected by the electrode, and ions of the same sign as the charge on the electrode are repulsed therefrom, and guard means substantially overlying said electrode and said radioactive means to prevent bodily contact with said electrode and said radioactive means, said guard means being formed of a material to prevent disturbance of the electrostatic field and having openings therein to permit the discharge of the desired ions and the collection of the undesired ions, the outer surface of said guard means being adapted to be substantially flush with said planar surface formed by the louvers.

5. An ion generator as in claim 4 together with a phosphor coated member nintimate contact with a portion 0f said radioactive means.

6. In an ion generator, a mounting member, a substantially planar electrode carried by the mounting member, a radioactive member centrally located with respect to said electrode and overlying the electrode in a plane parallel to the electrode, said radioactive member causing ionization of the air in the vicinity of the radioactive member to produce a dense plasma of positive and negative ions, a conductor member mounted in the mounting member and connected to the electrode, a power supply, means connecting the power supply to the conductor member in the mounting member to apply a charge of one sign to the electrode and to establish an electrostatic field so that ions of the sign opposite the charge on the electrode are collected by the electrode and ions of the same sign as the charge on the electrode are repulsed therefrom and a guard member supported by said mounting member and overlying said electrode and said radioactive member to prevent bodily contact with said electrode and said radioactive member, said guard member being formed of a material and in such a manner to prevent disturbance of the electrostatic field and to thereby permit the discharge of the desired ions and collection of the undesired ions produced by the radioactive member.

7. An ion generator as in claim 5 wherein said radioactive member is in contact with said electrode.

8. An ion generator as in claim 6 wherein said guard member is formed with a plurality of radially extending ribs defining a central opening overlying the radioactive member and a plurality of spaced openings overlying the electrode, the inner edges of the ribs being in contact with the electrode and the outer edges of the ribs being inclined inwardly toward the center.

9. An ion generator as in claim 6 together with a ringlike phosphor-coated member centrally disposed over said radioactive member and being in intimate contact with a portion of said radioactive member, the phosphor Y being rendered phosphorescent by the radioactive member, said phosphor-coated member being substantially transparent to permit viewing of the phosphorescence.

l0. In the combination of an ion generator with an air-conditioning unit, said air-conditioning unit including louvers through which the air is discharged, the outer surfaces of the louvers forming a substantially planar surface, the ion generator comprising a mounting disposed behind the planar surface formed by the louvers, a c01- lecting electrode carried by said mounting, radioactive means centrally disposed and overlying said collecting electrode in a plane parallel to the plane of the collecting electrode, said radioactive means serving to ionize the air in the vicinity of the same to cause production of a dense plasma of positive and negative ions, means mounted in the air-conditioner for applying a charge of one sign to the collecting electrode to establish an electrostatic field whereby ions of the sign opposite the charge on the electrode are collected by the electrode and ions of the same sign as the charge on the electrode are repulsed therefrom, and guard means substantially overlying said electrode and said radioactive means to prevent bodily Contact with said electrode and said radioactive means, said guard being formed of a material preventing interference with the electrostatic field and having openings therein to permit the discharge of the desired ions and the collection of the undesired ions, the outer surface of said guard means being substantially flush with said planar surface formed by the louvers.

ll. A combination as in claim 10 wherein said guard means consists of a plurality of radially extending fins defining a central opening overlying the radioactive member and a plurality of spaced openings overlying the electrode.

References Cited in the file of this patent UNITED STATES PATENTS 2,023,934 Moise Dec. l0, 1935 2,403,316 Wallhausen July 2, 1946 2,594,777 Hicks Apr. 29, 1952 2,785,312. Martin Mar. 12, 1957 2,850,641 Martin Sept. 2, 1958 OTHER REFERENCES Martin: Production of Unipolar Air With Radium Isotopes, Electrical Engineering, January 13, 1954, 6 pages.

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