THEORY OF THE VISCOSITY OF HELIUM II: PART 2. CALCULATION OF THE COEFFICIENT OF VISCOSITY

• Document Type: CREST
• Collection: General CIA Records
• Document Number (FOIA) /ESDN (CREST): CIA-RDP80-00809A000600280234-1
• Release Decision: RIPPUB
• Original Classification: C
• Document Page Count: 2
• Document Creation Date: December 22, 2016
• Document Release Date: September 21, 2011
• Sequence Number: 234
• Publication Date: January 20, 1950
• Content Type: REPORT

Sanitized Copy Approved for Release 2011/09/22 : CIA-RDP80-00809A000600280234-1
COUNTRY
SUBJECT
STOW
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DATE
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CLASSIFICATION CONPID IPIALCONFIRFNTIht1
CENTRAL INTELLIGENCE AGENCY REPORT
INFORMATION FROM
FOREIGN DOCUMENTS OR RADIO BROADCASTS CD NO.
Monthly periodical
Aug 1949
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DATE DIST. COa Jan 1950
NO. OF PAGES
REPORT NO.
THEORY OF I= VISCOSITY OF AELIOld II.
PART 2. CAT.CW.ATIOA OF THE CONFICISLIT OF VISCOSITI
The coefficient of viscosity of ordinary fluids decreases with tempera-
ture; thus, if eta lrt represents this coefficient of viscosity, then its
derivative with respect to temperature T, namely dY /dT, is negative. It
is found that dYl/dT for Selius II is negative everywhere except for a wall
region near the lambda point. Therefore, the temperature variation of helium
II's coefficient of viscosity cati&.it f?11= the 1ev anaerted by L. Tisza (see
Phya Rev, 72 839, 197), narelylj'....,T3 or the earlier egaeily erroneous re-
1attonD T$.
quantitatively, n(T) has been determined for the intervals T 1.O?K; and the above coapliccted
law governs the intermediate area between 0.7? and 1.0?K (Y1 at T~0.9?K
is found by extraan1&tinn) _ yl
CONNOENIIAL
_ I I _~ I I
I
Sanitized Copy Approved for Release 2011/09/22 : CIA-RDP80-00809A000600280234-1
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C, I'll NFiBEER T IAi
Actually, the above-mentioned coefficient of viscosity is the total
viscosity; that is, it is the sum of the so-called roton viscosity and phonon
viscosity. Thus, theory shows that \r (roton viscosity) in independent
of temperature and equals 1 ? 10-5 poise. It is r (phonon viscosity) that
varies with. T.
The kinetic equations for roton and phonon viscosity were solved by
use of the effective differential cross sections of scattering of the elemen-
tary excitations, phonons and rotons, which were obtained in Part I of this
work. Simplifying assumptions were made in order to effect a solution. Thus,
the distribution function n for rotons (or phonons) was assumed to be
close to its equilibrium function no; the sought-for stationary solutiou
permitted the elimination of partial derivatives with respect to time t;
alsa, the collision angles were assumed to be small; etc.
Of course, the analysis was carried out separately for the two tempera-
ture intervals T