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Патент USA US3066230

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Nov. 27, 1962
Filed Aug. 27, 1959
2 Sheets-Sheet 1
Nov. 27, 1962
Filed Aug. 2"’, 1959
2 Sheets-Sheet 2
rates atent Office
Patented Nov. 27, 1962
the above-described preferred features thereof, the inven
tion further comprises additional arrangements which
are preferably used at the same time.
Guy Nief, Paris, and René Batter, Chatillon-sous-Bagneux,
Seine, France, assignors to Commissariat a l’Energie
Atomique, Paris, France
Filed Aug. 27, 1959, Ser. No. 836,529
Claims priority, appiication France Aug. 30, 1958
4 Claims. (Cl. 250—41.9)
They are apparent
from the detailed description which follows, but the fol~
lowing among them will be particularly mentioned:
(a) An arrangement in which vacuum is set up in the
tube of the mass spectrometer with the aid of three pumps
in series, i.e. a conventional primary pump and two mer
cury-diifusion secondary pumps whereof at least one
10 comprises an ejector;
The invention relates to improvements in means for
the quantitative analysis of deuterium in hydrogen-con~
taining compounds.
As is well known the respective components of a gas
eous mixture of hydrogen and deuterium can be quantita
tively estimated by means of a mass spectrometer. How
ever, if it is desired to carry out a quantitative analysis of
the deuterium in hydrogen-containing compounds, as for
example in light water, H2O (as opposed to “heavy
(b) An arrangement in which the two ion currents
emanating from the mass spectrometer are separately
ampli?ed before their ratio is measured; and
(0) An arrangement in which the absolute value of the
proportion of deuterium in the hydrogen-containing com
pound being analysed (for example: a specific water),
is determined to a satisfactory approximation by relating
the numerical results of at least two measurements made
on the said water using at least some of the arrangements
water,” D20), it is advantageous to reduce such com 20 according to the invention, to the values of two substan
pounds in order to cause their hydrogen and deuterium
tially linear curves which express the quantitative analysis
to appear in the free gaseous state. Where this operation
of deuterium, in the liquid and vapour phase respectively,
is effected, it is very di?icult to prevent the reduction thus
in a mixture of hydrogen sulphide and reference waters
carried out from having a quantitatively distorting action
containing a specific mixture of pure light water and pure
on the reduction products; that is to say to ensure that
heavy water.
the proportions of hydrogen and deuterium obtained
In order that the invention may be more fully under
after reduction, and intended to be ionised and intro
stood, certain preferred embodiments thereof will now
duced into the mass spectrometer, are really the same as
be described, by way of example only, with reference to
the proportions actually present in the compounds under
the accompanying drawings, in which
investigation. Moreover, it is very important that the 30 FIGURE 1 is a diagrammatic overall view of apparatus
reduction should be effected rapidly, so that the consecu
for carrying out quantitative analysis by means of a mass
tive quantitative analyses can be carried out rapidly in
the mass spectrometer with su?icient accuracy to make
FIGURE 2 is a diagrammatic view of the “gas line”
forming a part of the apparatus illustrated in FIGURE 1;
the results obtained worthwhile despite the small propor
tion of deuterium with respect to hydrogen in the usual
run of hydrogen-containing compounds.
A principal object of the present invention is the provi
sion of means for quantitatively analysing deuterium in
hydrogen-containing compounds which overcome the dis
advantages described above and enable a high degree of 40
accuracy to be obtained.
FIGURE 3 is an electrical circuit diagram of an
arrangement incorporating the present invention adapted
to give expression to the analysis carried out by the
spectrometer; and
FIGURE 4 is a graph illustrating another arrangement
according to the invention adapted to make still more
advantageous use of the results given by a mass~spectrom
This invention consists broadly in quantitatively ana
lysing the deuterium contained in hydrogen-containing
eter analysing apparatus according to the invention.
compounds, by means of a mass‘ spectrometer which
separates ions having an atomic mass of two (i.e. that of
a hydrogen molecule) from ions having an atomic mass
details of the device for pumping out the tube 1, said
device being connected to the tube 1 of the spectrometer
by a pipe 4a. The gas line itself is included in a rectangle
FIGURE 1 shows a tube 1 of a mass spectrometer and
of three (i.e. that of a molecule consisting of a hydrogen
“gas line” which conveys the gases which are to be an
atom and a deuterium atom), the said hydrogen~contain~
alysed to the tube 1, a primary pump 4, which sets up
ing compounds being reduced in a device known as a “gas
the desired vacuum in said gas line, is connected thereto
line” located before the mass spectrometer and in which 50 by a pipe 4a. The gas line itself is included in a rectangle
the actual reduction takes place in a uranium reduction
outlined at 5; its construction which comprises the use
oven‘ disposed between the “leak” via which gas is in
of a plurality of the features of the invention, is shown
in detail in FIGURE 2.
troduced into‘the spectrometer and the spectrometer itself.
The mass spectrometer used is a modi?cation of a con
In preferred embodiments of this basic apparatus, it is
provided with one or more of the following additional 55 ventional spectrometer in which the tube 1 is curved
through 60° (in technical language, such a spectrometer
is said to have a “60° magnetic prism”), with a mean
(a) The uranium in‘ the reduction oven is in the form
radius of curvature of 5 cms., at the bend 6. The spec
of one or more tapes or the like, of, for example, between
4 and 24 cms. long, between 1 and 5 mms. wide, and very
trometer also comprises a source of ions 7, a source
thin, preferably between 0.1 and 0.4 mm. thick, the said 60 magnet 8 which focusses the ions in the source, slots 9
related to the side of the source, a main magnet 10 which
uranium being heated to a temperature of the order of
different de?ections to the two ion beams pro
600° C.;
duced, an electrical collector 11 for H? ions of mass 2,
(b) In the gas line, the gases pass through two capillary
and ‘a collector 12 for HD+ ions of mass 3; the spectrom
tubes, situated respectively on either side of the uranium
eter in question is therefore a mass spectrometer of the
reduction oven; and
“two-three” type.
(c) The strip or strips of reducing uranium are dis
Independently of the gas line and its particular reduc—
posed in a U-shaped silica tube, while the remainder of
tion device, a certain number of particular arrangements
the gas line preferably consists of a glass based on alu
have been developed for such a spectrometer; these ar
minium borosilicate and sodium, such as that commer
rangernents form part of the invention and contribute to
cially available under the name “Pyrex.”
the quality of the results which the invention makes it
In addition to the above-described basic apparatus and
possible to obtain. These arrangements are brie?y
described hereinafter without enlarging on explanations
be water) whose deuterium content is to be measured,
of the corresponding detail which will be well known to
to be introduced. The tap 22c enables a gaseous hy
those skilled in the art.
drogen-containing compound, such for example as hy
In one of these arrangements, the tube 1 is pumped out
drogen sulphide, to be directly introduced; for this pur
by means of three pumps in series, i.e. a primary pump 13,
pose it comprises a ground inlet 26 which can be ?tted
which is generally of the vane type, and two mercury
to a container ?lled with the gas to be investigated.
ditfusion secondary pumps 14 and 15. The pump 14 is
The uranium reduction oven 24 is disposed, as stated
equipped with an ejector. It is strongly heated, and pro
above, between the leak 27 through which the hydrogen
vides primary vacuum for the pump 15, which has a
containing gas in introduced into the spectrometer and
nominal delivery of 30 litres per second.
10 the spectrometer itself.
Being given ‘that, for pumping hydrogen as is the case
The uranium contained in the oven 24 is in the form
here, the pumping rate ‘depends especially on the power
of two very thin tapes 28a and 28b, each disposed in one
with which the pumps are heated (and moreover that it
branch of a U-shaped tube 29 which is preferably made
depends thereon in a different manner for the respective
of silica. Each of the two uranium tapes has the fol
molecules of H2 and HD, which could have unfavourable 15 lowing dimensions, length: 8 cms.; width: 2.5 mm., thick
repercussions on the accuracy of measurements being
ness: 0.2 mm. The advantage of using such a very thin
carried out), it is advantageous to provide, between the
sheet of uranitun is that the time taken for the gas to
pump 15 and a solid carbon dioxide trap 16, a constric
become diffused in the metal, which is proportional to
tion which limits the undesirable effects due to this
the square of the thickness of the latter, is reduced.
phenomenon, and also retards distillation of mercury
Reaction equilibrium, corresponding to saturation of the
from the pumps towards the trap 16. A gauge 17 of
metal, is thus reached in a very short time under the
known type and various traps and safety devices illus
above conditions—approximately a minute.
trated at 18 and 19 complete the pumping unit.
The advantage arising from the particular location of
The various pumping arrangements described enable
the uranium reduction oven follows from the considera
pumping to be kept up for more than six months without 25 tions speci?ed below:
interruption, the device according to the invention mean
It is known that uranium heated to a temperature of
while remaining highly e?icient and strictly accurate in
operation, without the heating of the pumps having any
approximately 500° C. quantitatively reduces certain hy
drogen compounds, such as water, hydrogen sulphide
and ammonia, to hydrogen. At this temperature, how
effect on the measurements obtained.
Another particular arrangement relevant to the spec 30 ever, the solubility of hydrogen and that of deuterium
in uranium are governed by different laws, and this dif
trometer concerns the source of ions for the latter. In
order to obtain large ion ?uxes, a ?lament emission cur
rent of 4 milliamperes is used, while the output slot 9
is 1.5 mm. wire; this produces a strong electric ?eld, of
ference in solubility could constitute a serious source of
error in a device similar to that of the present invention
if special measures were not taken to nullify it.
approximately 50 v./cm., in the ionisation chamber of 35 ever, if the reduction pressure is greater than the pres
the tube 1, and, in particular, almost completely pre
sure in the ion source of the spectrometer tube 1, the
vents the formation of H? ions, which would be unde
gas produced by reduction tends to flow on its own to
wards the spectrometer tube without any need for it
to be recompressed. Moreover, since total reduction
Another arrangement concerns the receiving slots which 40 is effected in the gas line, the hydrogen which passes
are one of the elements of the collector members 11 and
out of the oven when the reducing uranium is saturated
12 for each of the two ion beams and which enable the
with dissolved gas has the same isotope composition as
strength of the said beams to be measured. In order to
'the gas introduced into the oven. Nevertheless, the
facilitate adjustment, these slots are made relatively wide
quantity of uranium metal is preferably limited to that
(for example 0.5 mm.). Moreover, the planes of the two
present in tapes having dimensions of the order indi
slots are respectively disposed perpendicularly to the mean
cated above since the quantity of hydrogen-containing
axis of each of the two electron beams and, at least sub~
compound to be reduced is only that which gives rise
to the hydrogen which must, in fact, be introduced into
Ztantially, at the focal points of the corresponding ion
the ion source of the spectrometer tube. In addition,
The mass spectrometer and the collectors enable the
the pressure of hydrogen on the metal is very low, and
ion currents to be measured, preferably by means of an
the time taken for the uranium to become saturated is
electrical circuit as shown in FIGURE 3, which will be
consequently short, which acts in the same sense as the
described later. It is nevertheless important for the
fact, indicated above, that the metal is very thin.
gaseous currents of H2 and HD reaching the spectrometer
The gas line illustrated in FIGURE 2 also incorpor
via the tube 3 (FIGURE 1) to have a quantitative com- " ates a further preferred feature of the invention, namely
position which is a faithful reproduction of their propor
the provision of a capilliary tube on each side of the oven
sirable since in this case measurements are only carried
out on H24‘ and I-ID+ ions.
tions in the hydrogen-containing compound which is
24. ()ne capillary tube 27, constitutes the “leak” through
being analysed. This condition is satisfactorily attained,
which the gas to be reduced is “introduced” into the
in spite of the dif?culties which it involves by deduction,
by virtue of the particularly arrangements which the
invention provides for the “gas line,” disposed at 5,
wherein the hydrogen-containing compounds under in
oven. Suitable dimensions for the tube 27 are 10 cms.
long and an internal diameter of 0.2 mm. The other
capillary tube 30, which is disposed between the re
duction oven 24 and the spectrometer tube, is 5 cms.
long and has an internal diameter of 0.1 mm.
vestigation are reduced. FIGURE 2 illustrates in detail
the construction of such a gas line. The line, which is
located between the vacuum-pumping pipe 4a and the
‘pipe 3 which provides a connection to the mass spectrom
Introduction of the hydrogen-containing compounds
to be analysed into the gas line is effected, in the case
of liquids (water being the most commonly analysed
eter, comprises the following principal integers: a liquid
'nitrogenrtra'p 21 of known type; four taps 22a, 22b, 22c,
liquid), through the inlet 25 and, in the case of gases,
through the inlet 26.
If a liquid, for example water, is being dealt with,
22d; an expansion bulb 23; and a uranium reduction
oven 24.
70. it is introduced with the aid of a small helix 31 of plati
The tap 22a serves to isolate the gas line from the
vacuum-pumping device 4. The tap 22b enables an inlet
25 to be placed in communication with the expansion
bulb 23, while the inlet 25 enables a sample of any partic
ular liquid hydrogen~containing compound (this will often
num wire mounted on a polyvinyl plug 32.
is chosen because it is readily wetted by water and be
cause it resists corrosion; moreover, it is very simply
cleaned by heating the wire to red heat.
The following procedure is followed for introducing
the water (or other liquid) into the gas line: the plug
of standardised waters and hydrogen sulphide, as ordi
32 is attached to the inlet 25, and the taps 22b and 22d
are opened, while the tap. 22a and 220 are closed.
Opening of the tap 22d causes the Water held by the
nates, against the corresponding values of the ratio R,
small helix 32 to vaporise in the expansion bulb 23;
curves 37 and 38 do not extend as far as the intersection
as abscissae, the axes of the graph having an arbitrary
origin. The experimentally determined points on the
the latter advantageously has a volume of 250 cubic
point P, but they are graphically extrapolated to the
centimetres. The small quantity of air (approximately
point P. The ordinate of the point P represents the
0.05 cubic centimetre) between the plug 32 and the tap
actual Zero concentration of deuterium as this point rep
22d is, of course, simultaneously introduced into the bulb
resents the condition of H28 and H20 in equilibrium hav
23, but this does not involve any disadvantage, since IO ing the same concentration of deuterium, which can only
air combines with uranium at 600° C. to give oxides
happen with zero concentration of deuterium.
The standardised waters are obtained by mixing
and nitrides. The water vapour diffused through the
“light” water ‘and known quantities of substantially pure
capillary tube 27 then passes into the oven 24, Where
it is reduced to hydrogen which then passes on to the
heavy water.
ion source of the spectrometer.
Following such calibration, the device according to
Two further details of the improved gas line illus
the present invention is employed in the following way
trated in FIGURE 2 are as follows: one is that it is ad
in order to obtain a quantitative determination of the
vantageously constructed, before the U-shaped tube 29,
deuterium content of the hydrogen-containing compound
under investigation.
of a glass based on aluminum borosilicate and sodium,
for example that known by the trade name “Pyrex”; the 20
The ratio R is determined for different decreasing
other is that the taps are advantageously heated to ap
values of output voltage V of the ampli?er 33, the said
proximately 85° C. in order to prevent water from be
values being between 30 and 20 volts and being reduced
ing absorbed on the walls (the taps are therefore prefer
by reducing the pressure in the expansion bulb 23 of the
ably lubricated with a silicone grease), while the other
gas line by pumping out that part of the gas between
parts of the line are heated to approximately 160° C.; 25 the taps 22a and 22b. Each determination of the ratio
such heating is conveniently effected with electric heater
R takes approximately ?ve minutes and the results are
wires E-—E’.
then interpolated to obtain the reference value R0 of the
The apparatus illustrated in FIGURES l and 2 is
ration R corresponding to the reference output voltage
employed in conjunction with a device for measuring
of 25 volts.
ion currents, the latter device preferably incorporating 30 The device according to the invention is characterised
one or more of the features of the electrical circuit di
agram illustrated in FIGURE 3.
In the arrangement illustrated in FIGURE 3, the two
ion currents produced by the source 7 in the tube 1
by the possession of very ‘appreciable advantages, more
particularly the high degree of accuracy obtainable in
circumstances in which such accuracy has hitherto ap
peared to be unattainable, other things being equal, and
(which is illustrated here in a conventional simpli?ed 35 the relative rapidity with which such highly accurate
form), having been deflected in the tube as described
above with reference to FIGURE 1, are respectively
received by the collector member 11 in the case of H2+
results may be obtained.
In this connection, it may be mentioned that the ?eld
of use of a prototype constructed as above described
ions of molecular mass two and by the collector mem
with reference to FIGURES 1 ‘and 2 extends from zero
ber 12 in the case of HD+ ions of molecular mass three. 40 to 104 parts per million of deuterium in hydrogen, and
The ion currents received by these collectors are re
that the degree of accuracy obtained is 0.2 ppm. for
spectively fed by connections 33a and 34a to ampli?ers
concentrations of the order of a hundredth of a p.p.m.,
33 and 34 via pre-ampli?ers 33b and 34b respectively;
and 0.1% for stronger concentrations.
the ratio of the output currents of the ampli?ers 33 and
We claim:
34 is measured by a decade box 35a, 35b and a gal 45
1. In an apparatus for isotopic separation by mass
vanometer 36. If R is the ratio thus measured, the
spectrography of hydrogen elements of hydrogen con
concentration C of deuterium with respect to H2 is ex
taining substances reduced prior to separation, a mass
pressed by a mathematical function of R and the out
spectrograph, an ionisation chamber for said spectro
put voltage V of the ampli?er 33 relative to the ions
graph, means for delivering a reduced hydrogen contain
50 ing substance to said chamber comprising a gas line, a
of mass two, this function being:
tubular extremity for said gas line, a leak in said ex
tremity from said line leading to said chamber, a valve
where f(V) and F (V) are functions which take into
in said line, vacuum creating means connected to said
account certain undesirable phenomena in the mass spec
valve, a second valve in said line, means for admitting
55 hydrogen containing substances through said second valve
In addition a direct measurement cannot be made for
to said line, a tubular member under low pressure con
a given value of output voltage V since the latter pri
nected to said extremity and to said chamber and means
marily depends on the intensity of the beam comprising
in said member for completely reducing the hydrogen
ions of mass two. Furthermore, in order to express
containing substances including a reducing metal.
a ?nal result of measurement as accurately as possible, 60
2. Apparatus as described in claim 1 in which said
a re-calculated value R0 must be determined for R,
reducing metal is in solid state and has a large active
according to a particular feature of the present inven
surface area.
tion, for a predetermined reference value of the output
3. Apparatus as described in claim 1 in which said
voltage V of the ampli?er 33. In practice, this output
tubular member is U-shaped, heating means for. said
voltage is between 20 and 30, so that it has been found 65 member, a capillary restriction between said member and
convenient to adopt an output voltage V0 of 25 as the
said chamber, said reducing metal being uranium ribbon
reference value.
less than 0.4 mm. thick.
The constants f(V0) and F(VO) are determined by
4. Apparatus as described in claim 1 in which said gas
calibrating the mass spectrometer according to the in
line includes an expansion chamber.
vention before it is used for analyses; this calibration 70
References Cited in the ?le of this patent
leads to two linear curves which are indicated at 37
and 38 in FIGURE 4. These curves are obtained by
plotting the concentration C of deuterium, in the liqiud
Nier ________________ __ Oct. 25, 1949
and vapour phase respectively, in a plurality of mixtures
Huckabay ____________ __ Jan. 31, 1956
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