Triple Point of Argon

Abstract

of 2.5 cm long by 1.6 cm diameter copper tube having The triple point of pure Argon has been measured and the several overlapping copper baffles.value obtained is t* --189.3331 OC where t* refers to a tem-The differential thermocouple with its junctions at F a t W scale obtain& by extraPolati'% the Cal1endar-the sample chamber and the heat exchanger respecvan D w n equation. Several samples from two suppliers were tively showed that, in the initial design, at the triple The experiments indicated that large thermal gradiente may point of argon the heat exchanger was very much erraily be set up within the melting Argon sample and that warmer than the samde when in vacuum. It was and all the obtain& were within a qread rather careful heat leak control and e x b ~m e n k 1 p r o d m is necessary for precise melting point determination.

Studies of Phase Changes in Argon

“…I n an earlier determination of the triple point of argon [3] the resistance ratio obtained with thermometer #I521389 was W = 0.2159758. From calibration of this thermometer on IPTS-68 using the boiling point of 0, recently realized at NRC [2], this resistance ratio corresponds to the temperature T (NRC '68) = 83.797,K.…”

Modeling of the deposition of Na Clusters on MgO(001)

“…On the other hand, frozen Ar material is a very soft solid due to the weak Ar-Ar binding. The melting point of Ar is 83.78 K [59], much lower than that of MgO around 3073 K [60]. The softness of the Ar material thus changes the energy balance to the extent that the Ar substrate takes up most of the impinging energy, leaving rather little internal excitation for the cluster itself.…”

Development of the Sealed-Type Triple-Point-of-Argon Cell for Long-Stem SPRT Calibration at KRISS

“…The design of an apparatus for the cryogenic fixed-point calibration of long-stem SPRTs must take into account the fact that the available depth is limited by the distance between the sensing element and the head of the SPRT. Thus, a temperature gradient of >200 K occurs over a length <50 cm [3][4][5][6][7]. Therefore, controlling the heat flow is essential to realizing the cryogenic fixed point when calibrating long-stem SPRTs.…”

“…The cell is made of stainless steel, except for the lower part of the thermometer well, which is made of copper. The inner volume of the cell to be filled with the thermometric gas was calculated to be 234 cm 3 . In our design, if the cell is filled with argon gas at a pressure of 60 atm (6.1 MPa) at room temperature, then a depth of about 10 cm of solid argon will be formed at temperatures below the triple point of argon.…”