CERTAIN PROPERTIES OF SOLUTIONS OF HE3 IN HE4

• Document Type: CREST
• Collection: General CIA Records
• Document Number (FOIA) /ESDN (CREST): CIA-RDP80-00809A000600320262-5
• Release Decision: RIPPUB
• Original Classification: S
• Document Page Count: 4
• Document Creation Date: December 22, 2016
• Document Release Date: August 30, 2011
• Sequence Number: 262
• Publication Date: June 20, 1950
• Content Type: REPORT

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CLASSIFICATION SECRET
~~'
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sEC
!+C'RITDAI IRITCI I I!?CRIn~ A@CAIlTV
DCD/1DT
INFORMATION FROM
FOREIGN DOCUMENTS OR RADIO BROADCASTS
COUN~iRY USSR
CD NO,
DATE OF
INFORMATION
1950
SUBJECT Scientific -Helium
NOW
DATE DIST.~
Jun 1950
PUBLISHED
WHERE
PUBLISHED
GATE
PUBLISHED
Thrice-monthly periodical
Moscow
11 May 1950
LANGUAGE
Russian
SUPPLEMENT TO
REPORT N0.
TNI! ~OCV YENi CONTAINS INFORMATION AFFLCTINO TNL NATIONAL D[F[NS[
Oi TN[ UNITlD lTATF! WITHIN TNL Y[ANINO OF [S PIO NAOF ACT SO
Y. S. C., ]1 AND ]L. AS AN [N OLO. li! TRA Ml MISlION OR TN[ RLY[LATION
OF IT] CO NT[NTS IN ANY YANN[R TO AX UXAU TXO RI[EO P[RYON I! PRO?
NIBIT[0 BT LAW. RIPROOUCTION OI THIS FORM If PROHIBIT[ D.
Doklady Akademii Nauk SSSR, Vol LXXII, No 2, 1950.
CERTAIl4 PROPERTIES OF SOLUTIONS OF He3 IN Hey
~igures are appended-]
Many works on the separation of helium isotopes and on the properties
of pure He3 and He3-Hey mixtures have appeared during the last 3 years.
One reason for the great interest in these problems is the desire to
study the properties of liquid He3, a knowledge of which is essential in the
theory of He II, a~d to consider the phase transition He I - He II in solu-
tions of He3 in He Much interest is also attached to as complete a study
as possible of other physical properties oP He3.
The great difficulties in obtaining ~ure He3, or helium rich in this
isotope, result from the extremely low He content of ordinary helium. The
concentration of He3 in helium obtained from gas wells varies from 0.6 x 10-7
to 2.0 x 10-7 (1). The.He3 content in helium obtained from the atmosphere
is approximately one order higher, i.e., 1.2 x 10- (2). Because of the low
helium content of the atmosphere, however, it is very difficult in practice
to obtain it in quantities sufficient to extract the light isotope. There-
fore, helium from wells is usually used as the initial helium.
Because of the very low He3 content?of helium, ordinary concentration
methods are ~neYfectual (3-~). For this reason, the properties oP so3utions
of He3 in He have been little studied.
In our report, we cite briefly the results oP our studies in developing
an effective method for enriching the light helium isotope and in investi-
gating the dependence of th~ temperature of lambda transition (transition
of He I to He II) on the He content and the characteristics of the pheno-
mena oP overflow of He II along a wetting film in He3-He4 mixtures. Descrip-
tion of our enriching method has been deferred awaiting a detailed report
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and we note here only that a thermomechanical effect was initially used to
obtain approximately 1,000-fold enrichment, while a further 200-fold enrich-
ment was carried out in a distillation coltmtn. This degree of enrichment
does not represent the limit of the method, but was determined by the ne-
cessity of obtaining a final mixture of about 20 cubic centimeters for mea-
suring purposes. The mixtures used for measurements contained up to 1.5 per-
cent He3. The concentrations wer.~ determined Prom a comparison (differential
method) of vapor tensions over He and the mixture, by using data on the.va-
por tension of pure He3 (6) and assuming that Raottlt's law holds for these
concentrations.
The temperature of lambda transition with only several cubic centimeters
of liquid helium can be determined most conveniently by observation of the
temperature when the liquid tegins to overflow along a wetting film. For
this purpose, an instrument similar to P. G. Strelkov's instrument (7), modi-
fied for work with small quantities of the liquid, was employed to study the
overflow of He II along a film. Figure 1 shows the main part of the instru-
ment, i.e., the two legs of a thin-walled capillary tube (diameter approxi-
mately one millimeter) communicating along the helium film. The instrument
was immersed in liquid helium and carefully screened from radiation.
Since the legs of the vessel are of different lengths, the helium con-
densed in them (through the capillary tube) stands at differ?nt lengths.
When the temperature of lambda transition is reached, helium begins to over-
flow from the upper 1>g into the lower. The speed of overflow was determined
for various temperatures slightly below that of lambda transition, and the
position of the levels was read with a cathetometer. Since the speed of over-
flow close to lambda transition is a rapidly-rising linear function of tem-
perature, the temperature of He I-He II transition can be determined from
these measurements with an error not greater than 0.005 degree centigrade.
These meast*_?ements were made with liquid helium for He3 contents of
0.34 percent and 1.5 percent. Shifts (decrease) in the temperature of lambda
transition were within the limits of error of the measurements in the first
case e.~td was 0.02 degree in the second.
The result ootained does not confirm the theoretical consideratiot: of
either London and Rice (8) or Stout (9). The lamoda transition, in contrast
to the generally accepted point of view, was considered in the first work as
a transition of the first type and it was concluded that He3 content of more
than one percent in He IT was impossible; in the second work; it was fe~?nd
that the shift in the transition temperature was greater than the experi-
mental value and was of the opposite sign.
While the present work was being prepared fir publication, the work of
Abraham, Weinstock, and Osborn (10) was published on the shift in the tem-
perature of gamma transition, using He3 obtained from tritium, and the new
work of Stout (11), who used the results of (10). Our data on concentra-
tions, which lend themselves to comparison, differ markedly from the results
of these authors; thus, the dependence of the temperature of He I-He II
transition on admixture of He3, according to our data is ~- - 1.3 (g the
temperature of transition aad C the He3 concentration), while according to
Abraham, Weinstock, and Osborn -~= 5. According to these authors, the er-
ror in determining 9 was ~ 0.05 degree centigrade, which could not give
the correct dependency for low concentrations (around one percent).
Overflow Along a Film
A difference in overflow, along a film of mixture and ordinary He II
was revealed in determining the shift,of the gamma transition in the instru-
ment described. It is known that the speed of this overflow ir. He II does
~ECR~T
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not depend upon the difference of levels, and is constant at a given temper-
ature. In experiments with He4 .in the instrument described, the picture de-
scribed Baas actually observed. Something entirely different occurred with
helium enriched with He3. Ia this case, the speed of overflow decreases
rapidly as 'the difference of the liquid levels in the legs decreases and be-
comes very small when this difference reaches 1-1.5 mi111T?eters. Moreover,
the dependence of the speed of overflow 9 (cubic centimeters per centimeter
par second) on the difference of levels do is almost linear (see Figure 2).
For experiments conducted at a temperature close to lambda transition,
the overflow takes place at constant speed (slightly less than for ordinary
He II at the same temperature) until the difference of levels becomes small
and then decreases with further decrease in the difference of levels. Fur-
ther away from the lambda temperature, the difference of levels at which
the speed of overflow starts to decrease is greater, and for sufficiently
low temperatures (approximately 1.5 degrees Kelvin), it will no longer be
possible to replace the section with the constant speed of overflow. In the
interval of difference of levels where decrease of the overflow speed is ob-
served, this phenomena will take place in the same manner for different tem-
peratures, but will depend strongly upon the concentration of He3 in the liq-
uid.
The phenomena discovered may be explained in the following way. The
concentration of He3 increases in proportion to the overflow -- namely the
overflow of helium along the film from one leg to the other -- into that leg
from which helium flows out, since the superfluid part of helium, i,e., He4,
flows along the film. Acting simultaneously with this mechanism is the mech-
anism of equalization of concentrations through the gaseous phase. At tem-
peratures considerably lower than the lambda temperature, the overflow speed
is great and rapidly causes a considerable 4ifference in concentration. There-
fore, an osmotic pressure is created which woul~_ lima+, the overflow if the
concentrations were not equalized through the gaseous phase, and the helium
would overflow only up to a certain difference of levels. This has been ob-
served, although for a very low concentration, by Daunt, Probst, and Jonston
(12) in e*+ experiment in which equalization through the gaseous phase was
eliminated.
Because of the equalization of concentrations through the gaseous phase,'
the overflow speed is now regulated ty the speed of this equalization. The
speed of equalization of concentrations through the gaseous phase will de-
crease ,just as, consequently, will the overflow speed, in proportion to the
decrease of the difference of concentrations. At temperatures close to the
temperature of lambda transition, the overflow speed will be low, thus caus-
ing a low difference of concentrrations. In this case, overflow will take
place at constant speed until the difference of levels corresponding to the
osmotic pressure for low difference of concentrations is reached. Afterwards,
the overflow process will again be regulated by the speed of equalization of
concentrations through the gaseous phase.
In conclusion, we note that the original enrichment attained with a small
instrument in which a thermomechanical effect was used for effecting further
enrichment, allows us to assume that He Ii with concentrations of more than
30 percent He3 exists at a temperature of 1.4 degrees Kelvin. .
1. L. Aldrich and A. Nier, Phys. Rev., 74, 1225 (1948)
2. L. Aldrich and A. P1ier, ibid., 74, 1590 (1948)
3. B. McInter, L. Aldrich, and A. Nier, ibid., 72, 510 (1947)
4. A. Andrew and W. Smithe, ibid., 74, 496, (194$)
~ECC~T
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7.
n.
McInter, L.
Aldrich,
and A. Nier, ibid., 74, y46 (1948}
6.
S.
SidoriaY., E.
Grilly,
and E. Hammel, i'?id., 75, 3G3 (1949)
7.
P.
G. Strelkov,
ZhETF,
10, 743, (1940)
8.
F.
London and 0. Rice, Phys. Re?!., 73, 1188 (1048)
9.
J.
w. stout, ibid.;. 74, 605 (1948)
10.
A.
Abraham, B. Weinstock and D. Osborn, ibid., 76,
864 (1949)
11.
J.
W. Stout, ibid., 76, 846 (1949)
12.
J.
Daunt, R. Probst and H. Jonston, ibid., 73, 6,8
(1948)
~ppended figures follow_7
0 0. l 0.2 0.3 0, 4 O,S 0.6 0.7 08 0.9 /.0 /. / GH
dh --T
encge of2levelsefor $e3~g,:~the lp5ex 10-2_ar0urves 2nand 3 areshift d b~fleand
. 2 millimeters, respectively, along the abscissa. 1 1.47?K, 2 2.08 K,
3 2.1o?K.
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