Laser operation with closed gas and tuned duct pulsing

Gas laser apparatus comprising:

• means defining an optical resonant cavity having a gas inlet and a gas outlet within a substantially closed loop flow path for a lasable gas having gas laser states,
• means for cyclically pumping gas laser states within the cavity to cyclically produce lasing action, excess energy and pressure waves in the gas,
• means for coupling said lasing action out of said cavity,
• gas flow diode means coupled to said gas inlet for cyclically obstructing gas flow to the cavity,
• tuned duct means coupled to said gas outlet located in the gas flow path downstream of the cavity for receiving gas from the cavity for producing compression and expansion waves in the gas within the cavity upon pumping and gas laser states within the cavity, said tuned duct means establishing diode opening and closing by said compression and expansion waves to effect cyclic propulsion of gas around the gas flow path,
• means for controllably exhausting gas from said gas flow path,
• means for controllably injecting lasable gas into said gas flow path at a temperature substantially less than that of pumped gas in said duct;
• and
• means for controllably balancing the injection and exhausting of gas to substantially maintain predetermined gas conditions in the cavity for cyclic pulsed lasing operation.