US1145735A - Electric-wave detector. - Google Patents

Description

C. D. AINSWORTH.

ELECTRIC WAVE DETECTOR.

APPLICATION FILED JUNE I3. Isla.

Patented July 6, 1915.

LTTI'YI I3 IIIIIIT elements,

nun zwtswonrn, or we o i a ELECT til :u snCHUSETTs.

@VJE DETECTOR.

pecination of Letters Patent.

Patend duly u, t

application led .tune 13, 1:1913. Serial No. 773,317.

To all 'whom it may concern.'

Be it known that l, Cmsrnn D. AINS- won'rn, a citizen of the United States, residing at Worcester, inthe county of Worcester and State of ssachusetts, have invented new and useful Improvements in Electric-Wave Detectors, of which the following is a specication.

his invention relates to improvements in instruments for detecting electric 'waves or oscillations.

it is a well established fact that certain and also the mechanical compounds of such elements, possess the property of emitting radiations similar in character to the familiar Rntgen or X-rays, resembling such rays in their penetrating power, photographic action, and action upon electried gases. Such elements are uranium, thorium, radium and actinium, these elements being termed radioactive to denote this property.

Results obtained by prolonged observations and eriments on uranium and its compounds bring out the facts that the power of radiation belongs to the element itself and not to the substances associated with it; that the radiations are emitted spontaneously and' unaided by outside agencies and that this power of radiation does not deteriorate with time.

s tu g out the present invention, it is my purpose to employ these radiations for the rectification of alternating currents, and consequently, thedetecting of electric waves or oscillations, particularly for use in radiotelegraphy.l lt will be understood, however, that the use of such radiations elsewhere and for analogous purposes may be brought about. These radiations produce numerous advantages in radio-telegraphy in replacing the ionizing element now employed in the so-called audion and valve detectors.

lit has long been hown that gases, which under normal conditions are nearly perfect insulators of electricity, when in' a state of ionization and under the inuence of an electric field become conductors of electricity, permitting a unidirectional flow of current. llnradio-telegraphy, is employed in the so-called audion and valve detectors, ionization of the rareiied gas inclosed in a glass bulb being produced thermally,

this principle an incandescent filament being the ionizing element. Such detectors, however, although they are the most sensitive yet devlsed, have many defects. In the first place, thls type of detector is fragile, being inclosed in a thin glass bulb so that the iilament may, at all times, be readily observed. Again, while in operation they require a continuous current supply in View of the fact that the filament must always be incandescent to produce ionization. Furthermore, this current supply must be carefully regulated and, constant, otherwise overheatlng will greatly shorten the iilaments naturally short life, and lastly, it may be stated that instruments of this class, being fragile and requiring careful and intelligent manlpulation, are not practical in this art.

Among the many advantages, that a detector of the' audion or valve type in which a suitable radioactive substance, for instance, uranium, is made the ionizing element, will possess over other detectors of this type, are: First, such a detector can be made practically unbreakable. Second, no adjustment will be required owing to the fact that the detector will be permanently adjusted in the process of manufacture. Third, a separate source of energy for the detector will not be required for the reason that the ionizing radiations emitted by all radioactive substances are spontaneous, and fourth, such a detector may be used continuously without operating expense for an indefinite time. Y

ln the accompanying drawing, the gure is a diagrammatic view of an electric wave detector constructed in accordance with my present invention, and circuit connections therefor.

ln the present instance, I have shown my improved detector as comprising a cylindrical glass bulb l in which is disposed concentrically of the axis thereof a tubular anode 2 having fastened thereto one terminal of a conductor 3 sealed through one end of the bulb.

rl`he numeral l indicates a neutral electrode of woven wire disposed concentrically of the tubular anode l and having connected thereto one terminal of a conductor 5 sealed through the opposite end of the bulb.

cylindrical 'cathode 6 surrounds the electrode 4 and is disposed concentrically thereof and appropriately spaced `apart therefrom,

such cathode being preferably formed eol of woven wire of a mesh finer than that of the electrode 4. Leadlng from the cathode 6 and sealed through the end of the bulb 1 with the conductor 5 isa conductor 7 Arranged within the bulb 1 adjacent to one end thereof is a transversely disposedV disk 8 composed of suitable insulating material and having the center line thereof coaxial with the longitudinal center line of the bulb and the similar lines of the anode 2, neutral electrode 4 and cathode 6. A suitable form of'radioactive substance is indicated at 9 and may be either in the form of al suitable chemical compound deposited upon one face of the disk 8, or in the form of the metallic element itself mechanically secured to the disk.

In the present instance, the conductors 7 and 5 of the cathode and neutral electrode respectively are connected to the terminals of the secondary winding of a tuning transformer 10, while bridged across the terminals of the secondary winding of such transformer is a variable condenser 11, the conductor 3 of the anode 2 including in series receivers 12 and a source of energy such, for

' instance, as an electric battery 13 and havunder the influence of the electric field prov duced by the battery 13 between the anode 2 and the cathode 6 permits a unidirectional flow of current.

In the present instance, the anode 2 is connected with the positive terminal of the battery, while the neutral electrode 4 and cathode 6 are vnegative so that the current generatedby the battery 13 will tend to flow from the anode 2 to the electrodes 4 and 6. Under normal conditions, that is, when the transformer 10 is not excited, the rarefied gas within the tube 1 is in a state of ionization produced by the radiation from the radioeactive substance 9, while the volta e of the battery 10 is such that the potentia between the positive electrode 2 and the negative electrodes 4 and 6 is lower than the potential necessary to break down the electrical resistance of the ionized gas between such electrodes. Upon the induction of high frequency current in the secondary winding of the transformer 10, the current iows from one terminal of the secondary, through the battery 13, receivers 12, conductor 3, anode 2, through the ionized gas to the negative electrode 4, thence back to the remaining terminal of the secondary winding of the transformer by way of the conductor 5. Thus, the battery voltage is increased su# ciently to break down the resistance of the ionized gas, thereby producing a sound in the receiver 12. When the induced current falls to the zero period of the cycle, the resistance of the gas is restored and the battery current interrupted and during the second half cycle of the induced current, the.

current ows from one terminal of the secondary winding of the transformer, through the conductor 5, electrode 4, through the ionized gas to the electrode 6 and then back to the other terminal of the secondary winding by way of the conductor 7. When the induced current passes from the neutral electrode 4 to the cathode 6, the resistance .of the ionized gas is broken down thereby enabling the battery current to iiow as be- 'fore and produce a sound in the receiver.

As soon as the high frequency currents are induced in the secondar wlnding of the tuning transformer, the a ove cycle of operations is repeated, so that the signals represented by the electro magnetic wave passing through the primary of the transformer may be translated at the receivers.

While I have herein shown and described one particular form of ap aratus for carrying my invention into e ect, I wish itto be understood that I do not limit myself to the details of construction herein del` scribed and delineated, as modication' and variation may be made within the scope of the claims and without departing from the spirit of the invention.

I claim:

1. An electric wave detector comprising -an anode, a cathode and a neutral electrode disposed in a rarefied atmosphere, a receiving circuit including all of said electrodes,

and a Aradioactive substance disposed in proximity to said electrodes.

2. An electric wave detector comprising an anode, a cathode and a neutral electrode disposed in a rareed atmosphere, a receiving circuit including all of said electrodes, a radioactive substance disposed in proximity to` said electrodes, and means for intensifying the current in said receiving circuit.

3. An electric wave detector comprising an anode, a cathode disposed concentrically of said anode, and a neutral electrode disposed concentrically of said cathode and all of said electrodes being disposed in a rarefied atmosphere, a receiving circuit including said electrodes, and a radioactive substance in Aproximity to said electrodes.

4. An electric wave detector comprising a bulb having the air therein rareed, an

' anode within said bulb coaxial with the longitudinal axis thereof, a cathode disposed concentrically of said anode, a neutral electrede arranged concentrically of said cath- ISG meegaat tu;

and means for intensifying the current in m said receiving circuit.

lIn testimonywhereo I ax my signature in presence o f two witnesses.

CHESTER DREW AINSWORTH.

.Witnessesz FRANCIS Pf MCKEON, GEORGE H. Rien.

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