What is the purpose of VACUUM in a steam turbine engine?

Steam turbine steam heat is converted into mechanical work, the difference of the input steam temperature and steam to the exhibit represents the heat that is converted into mechanical work but also the loss .what is higher steam heat pad, the larger the resulting work and that means efficiency. Condensation of steam to expose the pressure lower than atmospheric pressure (vacuum), and the difference increases the vapor pressure at the entrance and at the entrance

The purpose of vacuum in the steam turbine engine is to collect the vapor in the turbine engine outlet which in turn these vapors will be water again then feeding it into feed water pumps then boiler then in turbine again. Just like a simple rankine cycle.