Strengthening the TCC Bound on Inflationary Cosmology

We show that the constraints which follow from the {\it Trans-Planckian Censorship Conjecture} for inflationary cosmology can be strengthened if the pre-inflationary universe was dominated by radiation. The resulting upper bound on the energy scale of inflation is $\eta \sim {10}^4\mathrm{G}\mathrm{e}\mathrm{V}$, close to the scale accessible to accelerator experiments.