US2640158A - Ion controller - Google Patents

Description

y 6, 1953 w. w. HICKS 2,640,158

ION CONTROLLER Filed Jan. 30, 1952 2 Sheets-Sheet l O '2 v .5 4 5 CM IN A/R AT 760 MM AND IERHNGE 0F ALPHA BiRT/CL [.5 FROM POlON/UM FIE-2+ INVENTOR. H/f/flam W f/fcA s 14770/Q/VE VI May 26, 1953 w. w. HICKS 2,640,153

ION CONTROLLER Filed Jan. 30, 1952 2 Sheets-Sheet 2 PIE I= INVENTOR.

W/W/am VIZ/791.0%:

Patented May 26, 1953 ION CONTROLLER William Wesley Hicks, San Francisco, Calif., as- Signor to Ionics, Inc., San Francisco, Calif., a

corporation of California Application January 30, 1952, Srial No. 269,065

4 Claims.

This invention relates to a device for selectively discharging negative ions into atmospheric air within an enclosed area such as a dwelling or a room. Particularly this invention relates to the utilization of a simple ion emitter consisting of a material such as polonium which emits alpha particles which. in turn, create both positive and negative ions, together with means for selectively filtering out positive ions from those ions thus produced and circulating the negative ions throughout a chamber or room.

It is well known that the presence of ions in a given space results not only from natural ionization processes, but also from the production of light ions by the action of electric fields, thermionic emission, radioactivity and in other ways. It is the production of light ions from a radioactive source to which this invention is directed.

It is an object of this invention to provide means for efiectively controlling introduction into a room or enclosed area of light ions of predetermined polarity, from a radioactive source.

It is a further object of this invention to provide a simplified means for effectively eliminating light ions of one polarity from those light ions produced by a radioactive source and to prevent their introduction into a specified area.

Other objects and advantages of the present invention will appear from the following specification taken in conjunction with the accompanying drawing in which:

Figure 1 illustrates in cross section a device incorporating my invention;

Figure 2 illustrates a device of the kind illustrated in Figure l in which a source of current such as a B-battery has been substituted for the source of current utilized in Figure 1;

Figure 3 illustrates the characteristics of alpha radiation from radioactive sources and is adopted from Crowther, J. A., Ions, Electrons, and Ionizing Radiations (8th ed), William Clowes and Sons, Limited, London.

Figure 4 illustrates a modification of the apparatus illustrated in Figure l, in which the source of alpha radiation is supported away from the walls of the electrode;

Figure 5 illustrates, in perspective, a modification of a component part of the devices illustrated in Figures 1, 2 and i, in which a semi-cylindrical surface forms the electrode; and

Figure 6 illustrates an end view of the same modification as illustrated in Figure 5.

As shown in Figure 1, I provide a base Hi which is adapted to support the remainder of the device which includes an electrode II which, in this instance, is in the form of a tube; anion emitter i2, which will more fully hereinafter be described; a source of electric current IS; a switch l4 and a rectifier [6.

The base in may be formed of sheet metal or any other suitable material and is adapted to provide a mounting for the remainder of the structure.

The electrode I l is preferably made of conducting material and is suitably mounted, upon and insulated from the base In. In the specific embodiment illustrated. and described herein, the electrode II is 1% inches (about 4.4 cm.) in diameter and 4 inches long. The ion emitter l2 consists of a piece of polonium foil approximately 1. inch square and comprising initially 1%.; millicuries. One edge of the emitter i2 is placed preferably at a distance of /9, inch longitudinally from one end of electrode H and is suitably mounted thereon.

The device is adapted to be connected to a suitable source of current I3 through a double-pole switch M as indicated. The current is adapted to be connected by the switch. i l to the rectifier IS. A positive connection to the rectifier is not required and the negative side is connected to the electrode H, supplying a negative charge to the electrode 1 I. e

I have found that with a negative potential of approximately volts on the electrode II this device is capable of maintaining a negative space charge in an average room or enclosed chamber as will more fully hereinafter be described.

Operation of the device may briefly be described as follows: The device is connected to a suitable source of outside current l3 and the circuit to the rectifier I6 is closed by operation of the switch M. A negative potential is thus supplied to the electrode II.

The ion emitting surface or element 12 radiates alpha particles which, in turn, create both positive and negative ions by collision with air molecules. Positive ions are attracted to and collected upon the negatively charged electrode l with the result that they are neutralized. The negative ions formed by the alpha particles are repulsed by the negatively charged electrode H with the result that they follow a path along the lines of the electrostatic force between the electrode II and the environment.

Becuse the 'polonium emitter I2 is placed near one end of the electrode l l, the negative ions seek an escape from the nearest exit which is the nearest open end of the electrode whereupon they are discharged into the room. The repulsion of the negative ions from the charged electrode and each other and their subsequent movement along the lines of electrostatic force toward the outlet results in a negative space charge in the room.

The maximum number of ion pairs in the case of pure polonium 210 and its salts is formed at about 3.5 centimeters from the source. However, in a source of the type used in my embodiment (which as shown in Figure 6 consists of a base plate 2| coated by a thin layer of polonium salts 22, which, in turn is covered by a rhodium protective covering 23), there is a substantially fiat surmum travel will approach 3.5 centimeters as indicated. Those alpha particles leaving the foil at an acute angle with respect thereto will pass through a greater thickness of the protective covering and therefore will form their ion pairs at a distance of less than 3.5 centimeters, as illustrated.

I have found, using measuring equipment similar to that described by J. A. Fleming Terrestial Magnetism and Electricity (rev. ed, by Dover, 1949) that when the electrode I l is of the dimensions previously described and the polonium emitter is of the size and quantity hereina-bove specified, a test room approximately 12 feet wide, feet long and 10 feet high will, within approxi mately ten minutes, contain a majority of negative ions in the ratio of 1200 negative ions per cubic centimeter to 400 positive ions per cubic centimeter.

The operation of the devices illustrated in Figures 2, 4 and 5 is similar to the operation of the device illustrated in Figure 1.

It will be obvious from the foregoing that this construction in which there is only one electrode does not provide an electrostatic field (in the ordinary sense) as specified in my co-pending applications Serial Nos. 169,051, 169,052, 169,053 and 169,054. I appreciate that in one sense an electrostatic field may be said to exist in the instant device, the same being formed between the relatively neutral charge of the environment and the negatively charged electrode I I. To this extent an electrostatic field does exist. However, the ordinary electrostatic field would result in the attraction of negative ions to the positively charged electrode with their resultant neutralization rather than in movement of the negative ions through one end of member I l.

The utilization of the principle of negative ions seeking the nearest exit permits the elimination of the auxiliary blower or forced circulation described in my CO-peIiding application Serial No. 173,813, although a small blower may be used to increase the dispersing of ions after they leave this device.

This overwhelming production of negative ions will in a few minutes result in a negative space charge within the area or room. The value of a negative space char e within an area or room is disclosed in my co-pending applications, Serial Nos. 169,051, 169,052 and 169,054 and my Patent No. 2,576,899 granted November 27, 1951. For example, I have found that preponderance of airborne matter, with a few exceptions, is positively charged. Dust, lint, pollen, dirt and other material are generally positively charged. This can be demonstrated in the laboratory by measuring the affinity of particles for a given charge by using a hot filament ion source in an ion col1ect ing tube. In the air within a normal room there are substantial numbers of ions of both signs, with the positive ions outnumbering the negative ions, tending thereby to create a positive space charge within the room.

It is well known that in air, light negative ions move at an average rate approximately twice that of light positive ions, hence negative ions are lost at a greater rate to the walls of the room than are positive ions, resulting in the formation of a positive space charge. I have found it is necessary to generate an excess of negative ions continuously in order to establish a net negative space charge in a given area or room. The light negative ions travellin faster than the light positive ions will diffuse through the air toward the walls of the room in a relatively short period of time and must continuously be replaced if a net negative space charge is t be maintained.

f course, it is obvious that my device described herein could be used to enlarge the net positive space charge, or for any other purpose for which a source of positive light ions is desired, by reversing the charge on the electrode.

I claim:

1. In an ion controller, a radioactive source oi. alpha particles, an electrode having a generally cylindrical surface terminating in an open end, means mounting said radioactive source in fixed relation to said electrode and in such position that the axial distance from said source to the said open end is substantially equal to one-half the maximum range of alpha particles in air and so that the distance from said source to said surface, measured along the path of alpha particles emanating from said source, is substantially equal to the maximum range of alpha particles in air, and means for applying a charge of one polarity to said electrode.

2. The method of producing a preponderance of ion of predetermined polarity in a body of air, comprising, the steps of; producing alpha particle radiation through a portion of said body of air from a predetermined position to ionize air in a limited zone, electrostatically moving ions 01 a predetermined polarity outwardly of said zone in one direction into said body of air and releasing said ions to said body of air, electrostatically moving ions of the opposite polarity in the opposite directions from said zone to a boundary thereof and there physically collecting said ions of opposite polarity and absorbing their charge.

3. In an ion controller, a radioactive source of alpha particles mounted on the inner surface 01' an open-ended tubular electrode at a distance from the open exhaust end thereof approximately equal to one-half the diameter of said electrode, which diameter is approximately equal to the maximum range of alpha particles in air from the radioactive source, and means for supplying a charge of one polarity to said electrode.

4. In an ion controller, a radioactive source of alpha particles mounted axially within an openended tubular electrode at a distance from the open exhaust end thereof approximately equal to one-half the radius of said electrode, which radius is approximately equal to the maximum range 0! alpha particles in air from the radioactive source, and means for supplying a charge of one polarity to said electrode.

WILLIAM WESLEY HICKS.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,914,883 Cottrell June 20, 1933 2,264,495 Wilner Dec. 2, 1941 2,497,213 Downing Feb. 14, 1950 2,524,227 Klein Oct. 3, 1950 2,574,632 Engelkemeir et al. Nov. 13, 1951

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