Radius of the exit electron beam pipe
Do we need a wider beam pipe transporting electrons into the beam dump? By Sept 2014 a 6 inch diameter pipe transports the beam to a place about 2m upstream of the first wall of the beam dump. The pipe ends with a thick flange connected to a 1.5 inch pipe transporting the beam through the wall. There is a girder with a valve between the flange and the wall. The flange became a hot spot during the first beam tune in May 2014. Would it help to install a wider pipe from the flange through the wall?
- The deflection of the electron beam from the photon beam in that area is about L=400cm
- The electrons deflected not more than r cm from the trajectory of the non-radiated beam go into the beam dump. The others dump their energy into the hall.
- The full power of the photons is WB·R, where WB is the power of the electron beam and R is the radiator thickness in R.L.
The energy dumped by the radiated electrons into the hall is
W=WB/Eo·R·∫dk·(Eo−k)/k, where Eo and k are the energies of the incoming electron and of the outcoming photon. The integration limits are Eo·(r/(L+r)), Eo
The increase of the exit pipe radius from 2cm to 4cm would reduce the power dumped in the hall by the radiated electrons by about 15%.