  This study presents investigations on pulsed loading of a magneto-optical
trap (MOT) on an atom chip in an UHV environment. Using three parallel
resistively heated Rb-metal dispensers activated by pulsed current supply,
approximately 3.0 $\times$ $10^{7}$ cold $^{87}Rb$ atoms were loaded into the
MOT. A current pulse of $\sim$ 24 A with duration of $\sim$ 10 s raised the
pressure in the chamber from 2.0 $\times$ $10^{-10}$ Torr to 3.3 $\times$
$10^{-10}$ Torr. Remarkably, the pressure recovery time after switching off the
dispensers current was found to be $\sim$ 600 ms, making a significant
advancement in achieving fast recovery of UHV environment surrounding the MOT
region. This study is very useful for laser cooling and magnetic trapping /
evaporative cooling of atoms on atom chip in the same UHV chamber.
