We describe the first continuous-wave (CW) measurements of the upward-going temperature wave in the self-organized-critical (SOC) state which forms in He-4 under conditions of downward heat flow near T-lambda under gravity. The CW technique permits measurements with extremely low (< 1 nK) excitation amplitudes, allows continuous measurement of the wave velocity as the SOC state grows, and has yielded the first quantitative measurements of the attenuation. The CW measurements appear to support predictions for the velocity but disagree with predictions for the attenuation. This new technique may help us understand the underlying mechanism of the SOC state.
|Title of host publication||CW measurement of the upward-going temperature wave in the helium-4 self-organized critical state|
|Publisher||AMER INST PHYSICS|
|State||Published - 2006|