The 1962 He3 scale of temperatures. I. New vapor pressure comparisons

Abstract

A compari so n o f R c3 and H c' vapor p ress urcs, (P a, P 4 ), has b een made i n a n apparatus d es igned to r edu ce the n umber and magn itud e of correct ions a ssociated w it ll t h e r efiu xin g fi lm in t il e H e' prC'ss u re sens ing t ub e and t he attached bUlb . The cr itical pressure of H ea has bee n red ete rm in ed to be at 873 .0 ± 1.5 mm Hg a t 0° C and standard gravity; t hc correspo nd ing temperatu re as meas ured by a H e' thermometer is 3.3240 ± 0.001 8° Ie on the 1958 H e'scale. T hese (P a, p .) compa riso ns and the 1958 H e' scale are t he basis of t h e 1962 H ea scale of temperat ures d erived and evaluated in the papers follow in g t his o ne.E mp irical inte rpolation eq uations conta ining only P a and P, a re d escribed by means of wh ich exist ing P, measuremen ts may be con ver ted to an eq ui vale nt P a. A comparison has bee n made between t hi s interpolatio n a nd a convers ion in wh ich t h e 1958 H e' and 1962 H ea scalcs are used as parameters. D e viat ions between t he two p rocedures ar c w it hi n t h e es t imated erro rs of t he (P a, P,) m eas urements.I n subs id ia ry experim ents on techn iq ues for H e' t hermometry a typical vapor press urc J;lu lb a rra ngement w as tested. It is shown t h at t h e )'eflu xing film introd uces a heat fl ux, Qr, a nd a res ult in g Ieapi tza t emperat ure drop, t; T k, between t he H e II a nd its con tain er, whi ch may a moun t to ma ny m illici egrees.T he feasibility of calculatin g t; T k fo r a part icular He' vapor press ure b ul b was stud ied.T h e necess ity of meas uri ng 6. 7\ /(h at least once in situ is p oi nted out. In add it io n, it is necessa ry to r ed eter min e t he fil m fl ow rate per iod ically at t he sa me time t hat H e' vapor p ress ure m eas u re me nts are being mad e.

Realization of the ITS-90 at the NIST in the range 0,65 K to 5,0 K using the3He and4He vapour-pressure thermometry

“…Weber [16] of the Physikalisch-Technische Bundesanstalt has made measurements from 0,65 K to 2,9 K with 3 He and from 2,6 K to 5,0 K with 4 He, with (99,73 % confidence level); over these ranges, his results disagree with our results and with up to . We have compared our results with those of RS and El Samahy by plotting our results using the and vapour-pressure/temperature relations [17,18]. Below 1 K, where the values from RS on disagree with those of the 1979 El Samahy measurements, our values on are approximately half-way between the two.…”

Gas phase thermal diffusion of stable isotopes

“…Noble gas isotopes have found uses in measurement standards [17]. Helium-3 has an exceptionally high vapor pressure at low temperatures (0.5 K) compared to other gases, which accordingly makes it most suitable for the present vapor pressure standard temperature scale at such temperatures.…”

Magnetic thermometry from 1 to 30 K

“…The pressure i n the manometer was a Before endi ng t h i s section, i t shoul d be menti oned t h a t several discussions on the techniques o f vapor pressure thermometry e x i s t i n the 1 i t e r a t u r e . ~u r i e u x ' s t h e s i s ( 11) and the papers which e s t a b l i s h T6* (4,5,6) were e s p e c i a l l y u s e f u l t o the author.…”