Improvements in Electric Spark Gap Apparatus.
Year: 1899

page_text: Date of Application, 14th Mar., 1899-Accepted, 8th July, 1899
COMPLETE SPECIFICATION.
Improvements in Electric Spark Gap Apparatus.
I, THOMAS BURTON KINRAIDE, of 38, Spring Park Avenue, Jamaica Plain, in
the State of Massachusetts, one of the United States of America, Electrician, do
hereby declare the nature of this invention and in what manner the same is to
be performed, to be particularly described and ascertained in and by the following
statement:-
The more recent developments in electrical matters; and particularly in the
line of experimental research in connection with static electricity, has developed
conditions requiring the discharge of such enormous potentials and amperage as to
render the apparatus heretofore provided for such purposes inefficient and largely
useless, for the reason that these enormous discharges which the electrician frequently
desires to experiment or deal with very quickly render inoperative or destroy such
usual apparatus.
Accordingly, it is the object of my present invention to provide a practically
indestructible discharge apparatus to meet the more exacting requireinents of the
present day, and to that end I provide a spark gap which is virtually self-recuperative,
and comprises opposite parallel discharge surfaces of considerable area, which, besides
their practically indestructible character, possess numerous very important advan-
tages all as will be more fully pointed out in the course of the following detailed
description of the apparatus, reference being had to the accompanying drawings
illustrative of preferred embodiments thereof.
In the drawings, Fig. 1 represents in side elevation a simple form of iny improved
spark gap.
Fig. 2 is a similar view shewing a modification.
Fig. 3 is a top plan view of the forin of apparatus shewn in Fig. 2.
I provide electrodes preferably in the form of opposite parallel discs g, g', the air
gap between whose frame surfaces constitutes the spark gap, the extended area of
these electrodes preventing the tendency of the condenser (for example) with which
my invention will ordinarily be used, to discharge until it has reached its maximum
charge, and also causing the discharge to be exceedingly sudden when it does take
place, and the discs not being liable to become unduly heated.
The spark gap constitutes virtually a self-recuperative condenser; as it were, the
parallel, and preferably plane, metallic surfaces g, g¹, being the discharge surfaces
which discharge through or across the intervening air dielectric. The air gap is
broken through when the voltage has exerted a sufficient strain upon the air to
rupture it. The larger the discs are, the greater condenser capacity will they have,
and hence the further apart they will spark.
At each discharge of the condenser a small portion of the plates g, g¹, is oxidized,
the successive discharges producing very thin oxidation here and there until the
entire surfaces of the two discs are completely oxidised. These discs may be made of
copper or other suitable conductor material.
Suitable means is provided for accurately adjusting these plates relatively to each
other and regulating their distance apart, or, in other words, for controlling the
resistance of the intervening gaseous dielectric, and referring to the drawings, where

page_text: I have shewn a preferred means for accomplishing my object, it will be seen that
provide a plurality of posts g² threaded at their upper ends and carrying shouldered
nuts on the shoulders of which is placed the top disc g².
The opposite plate g rests on a support or table g and is mounted loosely on a
post 5, being normally held downwardly by a spring 7 contained in a hanger or
housing depending from the table g said spring bearing at one end against the
flanged lower end of the hanger 7 and at its other end bearing against a washer g
retained by a screw g whose head enters a hole or recess in the plate g for centering
the latter.
The plate
is provided on its underside with a plurality of recesses or sockets,
herein shewn as three in number, which receive props or struts 910 projecting upwardly
from the base of the instrument.
These props 10 are of precisely equal length, so that they support the plate y in
absolute parallelism to its opposite plate g¹.
The support has depending from its lower side a stud g¹¹ which is engaged by
the bifurcated end g12 of a lever g13 pivoted at g¹ to a post on its base.
By this provision the most delicate adjustment is possible simply by swinging the
lever gone way or the other so as to incline the struts go more or less, and thereby
increase or decrease the distance between the plates g, gl, the nuts g" being depended
upon for the coarser adjustments of the plates.
In Figs. 2 and 3 I have shewn the plates g, g¹, as hollow and provided with water
circulation pipes g1, in order that they may be absolutely prevented from all heating
under extraordinary conditions.
Under usual conditions, however, this provision, is entirely unnecessary, it being
sufficient simply to provide the plates as shewn in Fig. 1.
When the adjacent surfaces of the plates have become entirely oxidized, the plates
may be turned over and their opposite sides used, and when both sides have become
oxidized, they may be readily removed and scoured off without destroying any of
their adjustments.
My apparatus makes possible the sudden discharge of a condenser after the latter
has reached a certain predetermined point, and said discharge is of great volume or
large amperage and of a very sudden and abrupt nature, as the current will not break
across the spark gap until it cannot help doing so, and when it does do so the discharge
takes place with a minimum heating effect, not interfering with the efficiency, with
very rapid and with very short and sharp oscillations incapable of being obtained
between a ball or point discharge gap.
The adjustment of the plates relatively to each other regulates the amperage
discharge of the instrument being discharged.
Having now particularly described and ascertained the nature of my said inven-
tion, and in what manner the same is to be performed, I declare that what I
claim is :-
1. A spark gap of the kind described, said spark gap presenting opposite parallel
discharge surfaces of relatively large areas, and means for regulating the discharge
distance between said parallel surfaces, substantially as described.
2. The herein described spark gap comprising opposite electrodes presenting
parallel discharge surfaces, one of said electrodes being supported on three or more
struts of equal length, and means for rotating said strut-supported electrode about
its centre, whereby its adjustment may be varied to and from the opposite electrode,
substantially as described.
3. A spark gap comprising two permanent large superficial areas parallel to each
other, constituting opposite discharge surfaces, and an interposed gaseous dielectric,
said disebarge surfaces having condenser capacity for breaking down the intervening
dielectric, and the latter automatically restoring or renewing itself, substantially as
described.
4. A spark gap comprising opposite hollow plates or discs having parallel discharge
surfaces, means for regulating the discharge distance between said surfaces, and

page_text: circulation pipes entering the same, whereby a circulation of water may be maintained
for keeping the plates or discs cool, substantially as described.
5. A spark gap comprising three or more posts, shoulders adjustable thereon, a
plate or disc supported on said shoulders, a second plate below the same, a support
therefor, three or more upright struts loosely engaging said support, and means to
rotate said support about its centre, whereby said struts are simultaneously and
similarly moved for varying the distance apart of said plates, substantially as
described.
6. A spark gap comprising a central post, a plurality of supporting posts, two
plates, one carried by said supporting posts and the other adjacent said central post,
three or more similar struts supporting said lower plate, a spring maintaining said
struts in proper supporting relation, and means to rotate the lower plate on said
central post, substantially as described.
7. A spark gap comprising a plurality of supporting posts, two plates, the lower
plate being pivotally mounted, three or more similar struts supporting said lower
plate, and the upper plate being supported by said supporting posts, a lever pivotally
mounted adjacent said lower plate and loosely connected therewith at its inner end
for rotating said plate and tipping said struts, substantially as described.
8. A spark gap comprising a central post, a plurality of supporting posts, two
plates, the lower plate being pivotally mounted concentrically to said central post, a
hanger depending adjacent said post, a spring between said post and hanger and
engaging the hanging at its lower end and held by the post at its upper end, three or
more similar struts supporting said lower plate, and the upper plate being supported
by said supporting posts, a lever.pivotally mounted adjacent said lower plate and
loosely connected therewith at its inner end for rotating said plate and tipping said
struts, substantially as described.
WM. BROOKES & SON,
55 and 56, Chancery Lane, London, Agents for the Applicant.