Table 3 The averaged forces \({F}_{\Sigma }\), \({F}_{s}\), \({F}_{n}\) and \({F}_{r}\) for grains in the structure, obtained from experimental data on the velocities of ceramic grains.
From: Experimental evolution of active Brownian grains driven by quantum effects in superfluid helium
Experiment | 1 | 2 | 3 | 4 |
|---|---|---|---|---|
THe | 1.72 K | 1.87 K | 1.87 K | 1.87 K |
\(\dot{{Q}_{p}}\), W/cm2 | 0.3 (20%) | 0.7 (40%) | 1.3 (70%) | 1.9 (100%) |
Quantum vortex density L, 1010 m-2 | 0.81 | 1.9 | 5.8 | 12.3 |
Mean distance between vortices \({\mathcal{\ell}}\), μm | 11.1 | 7.3 | 4.1 | 2.9 |
Average grain speed, mm/s | 0.22 | 0.52 | 0.96 | 1.12 |
Average grain acceleration, mm/s2 (over the ensemble of moving grains) | 21 | – | – | 320 |
Kinetic energy of grains \({E}_{k}={m}_{p}{v}_{p}^{2}/2\) in a laser beam, eV (at mp = 2.1‧10–10 kg) | 0.32‧102 | 1.8‧102 | 6.1‧102 | 8.3‧102 |
Diffusion coefficients: \({D}_{p}\), m2/s | 6.0⋅10–8 | 3.3⋅10–7 | ||
Resultant force \({F}_{\Sigma }\), 10–11 N | 0.44 | – | – | 6.8 |
Work done by \({F}_{\Sigma }\) :\({A}_{\Sigma }\sim {F}_{\Sigma }{d}_{p}\), eV | 1.1‧103 | – | – | 1.7‧104 |
Specific entropy loss, \({\Delta S}_{\Sigma }\)/Np, eV/K | 0.64‧103 | – | – | 0.9‧104 |
Force \({F}_{s}\) , 10–11 N | 0.7 | 1.4 | 4.2 | 8.9 |
Work done by \({F}_{s}: {A}_{s}\sim {F}_{s}{d}_{p}\sim {E}_{V}\), eV | 1.7‧103 | 3.5‧103 | 1.0‧104 | 2.2‧104 |
Specific entropy loss, ΔSs/Np, eV/K | − 1.0‧103 | − 1.87‧103 | − 5.6‧103 | − 1.2‧104 |
Force \({F}_{n}\), 10–11 N | 0.011 | 0.026 | 0.048 | 0.056 |
Force \({F}_{r}\) , 10–10 N | 0.65 | 2.0 | 6.23 | 13.1 |
