That bulb looks like a Terralux TLE-1S. If so, they are still around but are getting increasingly hard to find. Until recently there were a few on E Bay.

Most suppliers are phasing them out because of the screw base and falling demand.

Another model is the TekTite LS 407. Expensive and only from the manufacturer.

I am not sure how these bulbs would work with generators and fluctuating current. They are polarity sensitive and must be hooked up correctly or bye bye bulb.

Scroll down to my thread " Where can I get"