When I was a child , so a long time ago, at the Huntsville ( huntsville alabama )Space Museum they had a demo that was something that looked like a pie pan that

When I was a child , so a long time ago, at the Huntsville ( huntsville alabama )Space Museum they had a demo that was something that looked like a pie pan that was 10 feet across with Mylar stretched across it. And a tripod that was attached at the edge and stood over it. At the top there was a cone of metal and inside the cone was a copper tube that ran up one of the tripod legs and spiralled around the inside of the cone then ran down one of the other legs. They had a household vacuum cleaner attached to a tube at the bottom of the pie pan. When the turned on the vacuum the Mylar got sucked down and it made a parabolic surface. The sunshine was then focused into the cone and the turned on the water and it ran through the copper tube . It came out a stream of water for a few minutes but then turned to steam. Always loved that contraption.