Trigger of the rp- and $\alpha $p-process

X-ray bursts are driven by thermonuclear runaways in the atmosphere of accreting neutron stars. The runaway is driven by the $\alpha $p and the rp-process. These processes are triggered by the 15O($\alpha $,$\gamma )$19Ne and the 18Ne($\alpha $,p)21Na break-out reactions from the hot CNO cycles. New experimental data for the determination of these rates will be presented and the impact on the x-ray burst ignition conditions will be discussed.