Joule-Thomson expansion of charged Gauss-Bonnet black holes in AdS space

Joule-Thomson expansion process is studied for charged Gauss-Bonnet black holes in AdS space. Firstly, in five-dimensional space-time, the isenthalpic curve in $T-P$ graph is obtained and the cooling-heating region is determined. Secondly, the explicit expression of Joule-Thomson coefficient is obtained from the basic formulas of enthalpy and temperature. Our methods can also be applied to van der Waals system as well as other black hole systems. And the inversion curve $\tilde{T}(\tilde{P})$ which separates the cooling region and heating region is obtained and investigated. Thirdly, interesting dependence of the inversion curves on the charge $(Q)$ and the Gauss-Bonnet parameter $(\alpha)$ is revealed. In $\tilde{T}-\tilde{P}$ graph, the cooling region decreases with charge, but increases with the Gauss-Bonnet parameter. Fourthly, by applying our methods, the Joule-Thomson expansion process for $\alpha=0$ case in four dimension is studied, where the Gauss-Bonnet AdS black hole degenerates into RN-AdS black hole. The inversion curves for van der Waals systems consist of two parts. One has positive slope, while the other has negative slope. However, for black hole systems, the slopes of the inversion curves are always positive, which seems to be a universal feature.