Submitted manuscript, 8.91 MB, PDF document
Research output: Contribution to Journal/Magazine › Journal article › peer-review
Research output: Contribution to Journal/Magazine › Journal article › peer-review
}
TY - JOUR
T1 - The breakdown of superfluidity in liquid 4He : an experimental test of Landau's theory.
AU - Allum, D. R.
AU - McClintock, Peter V. E.
AU - Phillips, A.
AU - Bowley, R. M.
PY - 1977/1/4
Y1 - 1977/1/4
N2 - A single pulse time of flight technique has been used to determine the drift velocity v of the negative ions injected into liquid 4He from a field emission source. Measurements of v as a function of temperature T, pressure P and electric field E are presented within the range: 0.29 < T < 0.5 K; 21 x 10^5 < P < 25 x 10^5 Pa; 1 < E < 300 kV/m. The experimental results are in good agreement with Landau's theory of superfluidity. The data are used to demonstrate the inapplicability of two theories of super critical dissipation: by Takken, based on an assumption of coherent roton emission; and by Bowley and Sheard, based on the assumption of incoherent single-roton emission. The results are, however, shown to be in excellent agreement with Bowley and Sheard's incoherent two-roton theory, and the data are used to derive a numerical value of the matrix element. characterizing two-roton emission. The surprising absence of the single-roton emission process is discussed, and an upper bound is placed on the relevant matrix element.
AB - A single pulse time of flight technique has been used to determine the drift velocity v of the negative ions injected into liquid 4He from a field emission source. Measurements of v as a function of temperature T, pressure P and electric field E are presented within the range: 0.29 < T < 0.5 K; 21 x 10^5 < P < 25 x 10^5 Pa; 1 < E < 300 kV/m. The experimental results are in good agreement with Landau's theory of superfluidity. The data are used to demonstrate the inapplicability of two theories of super critical dissipation: by Takken, based on an assumption of coherent roton emission; and by Bowley and Sheard, based on the assumption of incoherent single-roton emission. The results are, however, shown to be in excellent agreement with Bowley and Sheard's incoherent two-roton theory, and the data are used to derive a numerical value of the matrix element. characterizing two-roton emission. The surprising absence of the single-roton emission process is discussed, and an upper bound is placed on the relevant matrix element.
U2 - 10.1098/rsta.1977.0008
DO - 10.1098/rsta.1977.0008
M3 - Journal article
VL - 284
SP - 179
EP - 224
JO - Philosophical Transactions of the Royal Society of London A
JF - Philosophical Transactions of the Royal Society of London A
SN - 0264-3820
IS - 1320
ER -