Following optimization, the DNP build up for the ASE is compared to the NMR saturation recovery, shown in Fig. . The rise time of the optimized ASE is estimated to be 𝑇 0123 ≈ 250 s, significantly shorter than 𝑇 $. ≈ 460 s. Fig. shows the comparison of the DNP enhanced solid echo signal with the optimized 40 MHz frequency swept ASE pulses (see Fig. ) and the thermal signal (scaled by 100, taken overnight with recovery time of 1800s ∼ 4 × 𝑇 $. ). A slightly higher power (~300 W) was made available from the EIK by manually overriding the control software for this experiment, resulting in an enhancement of ε ∼ 496. The error in the measurement is estimated to be 5%, mainly from uncertainty in the thermal signal. As the DNP rise time is much faster than the nuclear spin lattice relaxation, the NMR signal for microwave εon/εoff can be even larger when the nuclear spin polarization is not yet fully recovered, e.g. εon /εoff > 1000 at the same 150 s time of DNP build-up and nuclear spin polarization recovery. In this case, DNP not only enhances the NMR signal, but also reduces the repetition delay allowing faster NMR acquisition and an even larger increase of the signal-to-noise per unit time than the enhancement alone implies.