Preliminary Design of Electron Beam line F. Velotti, C. Bracco, B. Goddard and M. Meddahi

Outline Geometrical layout –O–Overview –M–Matched parameters Elements –D–Dipoles –Q–Quadrupoles –B–BPMs –C–Correctors Preliminary Optics design Conclusions and open questions

Geometrical layout X Z 4223 Y 2380 X Z Y MAD-X global reference system

Geometrical layout It has been assumed zero vertical angle at the exit of the RF gun The e- beam arrives orthogonal to the plasma cell It is m (from the RF gun to the entrance of the plasma cell) The initial horizontal angle can be optimized in order to use the proposed tunnel RF Gun Already designed tunnel

Geometrical layout It has been assumed 5 cm (?) offset between the electron line and the proton line at the entrance of the cell The required deflection angle to deflect the e- beam on axis with p+ beam in 3 m is mrad (assuming the first bend at the entrance of the plasma cell) This will lead to a Dx different from zero, unless quads are used (at least 2 to close the dispersion)

Outline Geometrical layout –O–Overview –M–Matched parameters Elements –D–Dipoles –Q–Quadrupoles –B–BPMs –C–Correctors Preliminary Optics design Conclusions and open questions

Elements – Dipoles 3 vertical and 2 horizontal bends magnet L_yoke = 340 mm I_max = 330 A = T.m (20% needed assuming p=20 MeV/c)

Elements – Quadrupoles 4 defocusing and 5 focusing magnet L_yoke = 200 mm g_max = T/m (12.7% needed) I_max = 100 A R = 40 mm (good field = 30 mm)

Elements 9 BPMs (1vs1 strategy) for the 9 quads 2 for the final focus 1 at the exit of the RF gun L = 80 mm 9 horizontal/vertical correctors to cover all quads 4 just before the plasma cell entrance for the final focus L = 82 mm Chosen among the ones installed at facility BPMsCorrectors

Outline Geometrical layout –O–Overview –M–Matched parameters Elements –D–Dipoles –Q–Quadrupoles –B–BPMs –C–Correctors Preliminary Optics design Conclusions and open questions

Preliminary optics design Parameters at the exit of the RF gun Parameters requested at the entrance of the plasma cell Parameters obtained at the entrance of the plasma cell

Preliminary optics design Entrance of the plasma cell Entrance of the plasma cell Vertical Bends Horizontal Bends

Outline Geometrical layout –O–Overview –M–Matched parameters Elements –D–Dipoles –Q–Quadrupoles –B–BPMs –C–Correctors Preliminary Optics design Conclusions and open questions

Conclusions Preliminary design of the e- beam line at 20 MeV satisfies geometrical and optical requirements All the main magnet parameters are guessed starting from existing hardware (still missing iteration with CERN experts)

Open questions Commercial magnets or develop new at CERN? Beam size at merging point – Also, effect of the plasma on the e- beam Offset between p+ and e- beam (any constraints?) – Requirements about the 2 bends in the plasma cell (strength, aperture, etc..) Common beamline instrumentation (BPMs)