Aïn Oussera or Aïn Oussara (Arabic: عين وسارة) is a city in Djelfa Province, Algeria, with an estimated (2005) population of 134,174. It is the district seat of the Aïn Oussera District. The city has experienced rapid population growth in recent years due to its proximity to the 15 MW Es Salam nuclear reactor. Aïn Oussera is on the crossroads of the N1 (Trans-Saharan) and N40B highways. The nearest airport is the Algerian Air Force's Aïn Oussera airfield (DAAQ).