He was just crossing the street and suddenly he knew what he had to do!
Last year, I could speak with physicist Godehard Wüstefeld, who is one of the leading experts of the BESSY VSR project, here is the interview (short version) again. The full text is available in english here and in german as audiofile here:
BESSY-VSR does not have just one superconducting cavity but two. Why is that?
Godehard: It's a special trick that allows us to simultaneously accommodate both short and long electron packets. The idea being that we're able to create a kind of beat within the electric fields so that the electrons sometimes see the sum of the electric fields and the difference at other times. And that's the new idea, which was added later-on and which gives the project its appeal. It allows us to store the long electron pulses inside the ring and turn on the usual user settings and then the short pulses will only get into those areas where the fields overlap.
And how did this idea of a beat come up?
Godehard: We had discussed the possibility of BESSY-VSR some four years ago. Our goal was to produce short and long pulses simultaneously but we found that you can't really do it in the way it was talked about up until then. And after that meeting I walked over to my office, which was located in a different building, in the Willi Wien Lab, and on the way I had this idea that all we had to do was take two voltage clamps, produce an oscillation, and voilà! And then I started to do initial calculations, which helped confirm everything, and then we went ahead and published our first paper in 2011, presenting our ideas.
And this idea came to you just like that?
Godehard: Yes, I was just crossing the street and suddenly I knew what I had to do!