Abstract: A power efficient continuous wave gas ion laser system, associated laser tube and method are described. The system uses a fixed electrical input power and a power factor corrected power supply producing an output voltage and an output current from the fixed input electrical power. A gas ion laser tube is configured for use in the system having a particular cavity length which is established as a distance between a first mirror and a second mirror for operation using the output voltage and the output current. The system may be configured to provide a light output power improvement of approximately thirty percent over prior laser systems. In one feature, a laser tube is configured for providing the improved light output power in a conventional laser head configuration such that the laser tube may directly replace laser tubes in prior installations. Existing and new laser installations may benefit.