Dust particle pair correlation functions and the non-linear effect of interaction potentials
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Dust temperature is a measure of the energy of the stochastic motion of a dust particle, and is a result of the combination of the Brownian motion and the fluctuations in the dust charge and confining electric field. A method using the equilibrium value of the mean square displacement was recently introduced to obtain the dust temperature experimentally. As a follow up, this paper investigates the relationship between the temperature derived from the mean square displacement technique and a technique using the probability distribution of the displacements obtained from random fluctuations of the dust particle. Experimental results indicate that the harmonic confinement potential acting on the dust particle can be obtained by combining the two methods, allowing the non-linear effect of the confining force to be investigated. The thermal expansion in a one-dimensional vertical chain is discussed as a representative application as it is related to the non-linear confinement force, or the asymmetric confinement potential.