Twisted conjugacy classes in Chevalley groups

We prove that Chevalley group over the field $F$ of zero characteristic possess $R_{\infty}$ property, if $F$ has torsion group of automorphisms or $F$ is an algebraically closed field which has finite transcendence degree over $\mathbb{Q}$. As a consequence we obtain that the twisted conjugacy class $[e]_{\varphi}$ of unit element is a subgroup of Chevalley group if and only if $\varphi$ is central automorphism.