Evening star., 1925-09-06
THOR|ATED TUBES
/ AID TO ICE PATROL
New Radio DeteCtor, Found
by Accident, Making Ocean
l.. Travel Still Safer.

INdNuo Is making ocean lraNel SIlIl
safer, L. A. Hawkins, engineer in
charge of the research laboratories of
the General Electric Company. Sche-
nectady, n. Y, says in a narrative of
scientific progress issued by the Engi-
neering Foundation of New York, the
research agency of the four Founder
Societies of Civil, Mining and Metal
lurgical, Mechanical, and Electrical
Engineers.
New safeguards are being developed
and the ice patrol is now able to flash
warnings without interfering with
commerce or broadcasting. Thoriated
tungsten tubes, product of science and
accident, are described as a forward
step in radio transmission both in
the direction of science and in pre-
venting the loss of human life.
Of this invention, which combines
thorlum and tungsten, both metals,
Tor new uses to mankind, the Foun-
dation's narrative says:
Ice patrol warnings from this
equipment, while reaching much
farther than ever before, will no
longer be source of interference
with commercial traffic and broad
cast entertainment Under favorable
conditions it is expected that direct
communication viii be had with
headquarters in Washington"
Titanic Brought Research.
Two great objectives of scientific
research are elevation of human life
and saving of human lives, according
10 the narrative, which says that
civilized nations were shocked into
scientific achievement by the loss of
the Titanic in 1912. Ono of the i'm
mediate consequences was that the
United States undertook the ice pa
troll of the north Atlantic at the re-
quest of the International Conference
on Safety of Life at Sea.
Charged with so great a response
bility," the narrative continued, "our
Government has constantly been alert
TO utilize every aid which science
could afford.
Not long ago, two Coast Guard cut
terS. the Tampa and the Modoc en-
ployed in the patrol, were equipped
with the highest powered telephone
and telegraph radio transmitters car
rled by any ship under the American
flag. These transmitters contained
recently invented thoriated tungsten
tubes.
"Thorium was one of the sub
stances found to be radioactive. soon
after Becquerel's discovery of radio
activity and the finding of radium by
the Curies. The present invention
combines thorium and tungsten for
new usefulness. Tungsten is now
household friend in electric lights, and
thorium in one of its forms illumi-
mates many a watch face.
Placing Icebergs.
Success for the ice patrol consists
not only in finding bergs, but also in
conveying quickly TO ships at sea
exact information of the whereabouts
of these menacinG foaters. Most ships
traversing the Atlantic are now
equipped with radio apparatus; hence
the fitting of these patrol boats with
the best radio transmitters which
could be produced.
For the purpose of providing de-
pendable, long-range, high powered
transmitters. the Coast Guard COM
missioned the General Electric Com
pany to develop transmitter espe-
cially for the ice patrol. The equip
ment had to be so compact that it
would fit into a small radio room.
Due to its compactneSS, the volt
ages generated We're required to be
minima and the panels to be all of
the dead front type so that the oper-
ator would not be exposed to danger
Gus voltages if thrown against the
apparatus in heavy seas.
Strength, reliability and simplicity
of tuning also We're demanded. The
emitted wave length, or frequency,
variations due to rolling and pitching
of the ship. All these requirements
were met.
Tube Was Problem.
Greatest among the problems was
the development of a high-powered,
low-voltage vacuum tube. Available
were lOw-voltage tubes, using up to
1000 volts direct current obtained
from a motor-generator, and high.
voltage, operating on 10000 volts or
more of direct current.
ITO have provided this latter high
voltage on shipboard would have re-
quired a motors generator set, a STEP
up transformer, a rectifier with two
or more kenetron tubes and an elabo-
rate filter to smooth out the ripple in
the rectified wave,
Research specialists produced
new. tube rated at Only 1000 volts on
the plate, but four times as powerful
as previous 'low-voltage tubes Its
output is 1000 watts. BY means of
this tube power is supplied from the
direct-current motor generator set,
eliminating the transformer, kenetron,
rectifier and filter, heretofore neces-
Sary.
Discovery and DEVELOPMENT of
thoriated tungsten for this purpose re-
suited from the combination of a
scientific investigation and a happy
accident. Investigation of the So
called Edison effect in incandescent
lamps by DR.. Irving Langnuir led to
a more searching study of factors gov
erning emission of electrons from hot
flaments.
In one series of experiments with
tungsten filamentS, as the vacuum
was made higher and higher, electron
emission unexpectedly became stead
lily greater, until finally, when the
bulb was immersed in liquid air, the
emission was 10,000 times its original
value.
Thorium Discovered.
This was an astonishing result;
but when the experiments were re-
peated. with another lot Of wire no
such increase in emission developed
An investigation of the two lots of
wire revealed the fact that the second
was pure tungsten, but the first con-
tanned thoria, often used in lamp fila
mentS TO prevent excessive grain
growth on burning, which induces
fragility. This enormous increase in
emission would not have been OBJ
served under other than the very spe-
Cial conditions of the experiment
Further study disclosed the fact
that when a tungsten filament con-
tanning thoria is operated under the
right conditions the thoria is reduced
to thorium, which diffuses to the sur
face and there forms a continuous
layer one atom deep. The eIectron
emission is then that Of thorium.
which is much higher than that of
tungsten, while the high affinity OF
thorium for tungsten prevents the
surface thorium from evaporating as
it would if the whole filament were
thorium.
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