The Observed Properties of Liquid Helium at the Saturated Vapor Pressure

AcknowledgementsThere are a number of people I would like to thank for their contributions to this thesis. My advisor David Goodstein was insightful, encouraging, and patient throughout the many challenges of performing a low-temperature experiment. Our conversations were always helpful because David has an extraordinary ability to make complicated concepts seem simple and intuitive. I had two mentors in the lab, Peter Day and Richard Lee, who taught me everything I know about performing experiments in low-temperature physics. My first lab experience was working with Peter. He provided me with the cryostat I used throughout my graduate career, answered hundreds of questions, and patiently showed me the techniques I needed. Richard returned to Caltech as my thesis experiment was taking shape. He was also an excellent resource for the tricks and techniques of low-temperature physics. (Plus, he made B.O.B.2, the electrical filtering system on this cryostat). However, what helped me most was that he patiently asked hundreds of questions, which forced me to think through all the details of my experiment. It is with his help that I avoided many pitfalls.There are a number of other physicists who made significant contributions to this work. Particularly helpful were the members of the DYNAMX team from the University of New Mexico (Rob Duncan, Dimitri Sergatskov, Alex Babkin, and Steve Boyd). They provided material help with the cryo-valve system and the construction of the experimental cell. In addition, they provided a lot of expertise on performing experiments on the SOC state of 4 He. In particular, I would like to thank Rob Duncan, who served as a secondary thesis advisor during a critical time in the experiment as David Goodstein recovered from an injury. Also helpful were discussions with two theorists, Peter Weichman and Rudolf Haussmann, who helped give meaning to my results.I would like to thank my parents for many many years of encouragement and support, and not asking me too often when I was going to get my degree.I would also like to thank my wife Avital, who provided an enormous amount of support and, through an intricate dance of prodding and patience, helped guide me through this endeavor. Lastly, I thank my son Jacob, whose arrival helped destroy the illusion that maybe, just maybe, I could be a graduate student forever. We report the first results of the heat capacity of the SOC state, C ∇T , for heat fluxes 60nW/cm 2 < Q < 13 µW/cm 2 and corresponding temperatures 9 nK > T SOC − T λ > −1.1 µK. We find that C ∇T tracks the static (i.e., zero heat flux) unrounded (i.e., in zero gravity) heat capacity C 0 with two exceptions. The first is that within 250 nK of T λ , C ∇T is depressed relative to C 0 and the maximum in C ∇T is shifted to 50 nK below T λ . The second difference is that at high heat flux, C ∇T is again depressed relative to C 0 with the departure starting at about 650 nK below T λ .We present the most extensive measurements of the speed and attenuation of the SOC wave to date. We report wav...

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“…The compressibility at 2.7 K is 1.87 × 10 −5 torr −1 [18]. Finally, at 2.7 K, SVP is 111 torr [19]. From this we compute the bubble size as…”

Section: Cavitating the Bubblementioning

confidence: 99%

“…When superflow breaks down, the top endplate warms quickly and evaporates some of the helium which increases the pressure in the bubble. Using the SVP fit from Donnelly [19], the 35000 nK temperature rise that we see in fig. 3.3(a) increases the pressure in the bubble by 0.442 Pa.…”

Section: Cavitating the Bubblementioning

confidence: 99%

Experiments on the Self-Organized Critical State of 4He

Chatto

Lee

Duncan³

et al. 2007

J Low Temp Phys

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“…The corresponding 4 He densities are interpolated with the help of data from Ref. [29]. Although transition II was not observed at gas densities higher than 32 g/l [4], the calculated resonance shifts are also given here for this line, for the sake of comparison.…”

Section: Collisional Shift Of Resonance Linesmentioning

confidence: 99%

Shift and broadening of resonance lines of antiprotonic helium atoms in liquid4He

Adamczak

Bakalov

2013

Phys. Rev. A

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The shift and broadening of the resonance lines in the spectrum of antiprotonic helium atoms pHe + located in fluid and superfluid 4 He have been estimated. The contributions to the shift and broadening from collective degrees of freedom in liquid 4 He have been evaluated using the phenomenological response function. The shift due to collisions ofpHe + with 4 He atoms has been calculated in the quasistatic limit using the experimental pair-correlation function. It has been shown that an implantedpHe + atom establishes a good probe of liquid-helium properties, since this atom practically does not change the target structure.

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“…Here, we have used the density ρ = 145 kg/m 3 [46] and surface tension σ = 3.54×10 -4 N/m [46] of liquid helium at low temperatures. The relevant temperature in the nozzle expansion is likely about 4 K with a smaller σ = 1.1×10 -4 N/m [46], which will further reduce the estimated value of R. As discussed previously [29], at T 0 ≈ 5 K the fluid may separate into large droplets and a dense gas inside the nozzle, which continues to expand along the nozzle channel. Thus, if the droplets are produced before exiting from the nozzle, collisions with walls may contribute to the calculus of the droplet's angular momentum.…”

Section: Formation Of Rotating Droplets In the Free Jetmentioning

confidence: 99%

Shapes of rotating superfluid helium nanodroplets

et al. 2017

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Rotating superfluid He droplets of approximately 1 μm in diameter were obtained in a free nozzle beam expansion of liquid He in vacuum and were studied by single-shot coherent diffractive imaging using an x-ray free electron laser. The formation of strongly deformed droplets is evidenced by large anisotropies and intensity anomalies (streaks) in the obtained diffraction images. The analysis of the images shows that, in addition to previously described axially symmetric oblate shapes, some droplets exhibit prolate shapes. Forward modeling of the diffraction images indicates that the shapes of rotating superfluid droplets are very similar to their classical counterparts, giving direct access to the droplet angular momenta and angular velocities. The analyses of the radial intensity distribution and appearance statistics of the anisotropic images confirm the existence of oblate metastable superfluid droplets with large angular momenta beyond the classical bifurcation threshold.3

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The Observed Properties of Liquid Helium at the Saturated Vapor Pressure

Cited by 542 publications

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Experiments on the Self-Organized Critical State of 4He

Experiments on the Self-Organized Critical State of 4He

Shift and broadening of resonance lines of antiprotonic helium atoms in liquid4He

Shapes of rotating superfluid helium nanodroplets

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