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Injection in EMMA FFAG

Injection in EMMA FFAG. Takeichiro Yokoi(Oxford University). Requirement for injection(extraction) scheme. Energy Range : 10MeV~20MeV(variable) Beam Emittance: 3000 mm·mrad(normalized) (if possible, 6000mm·mrad for margin) Aperture :>45mm(Horizontal and vertical)

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Injection in EMMA FFAG

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  1. Injection in EMMA FFAG Takeichiro Yokoi(Oxford University)

  2. Requirement for injection(extraction) scheme • Energy Range : 10MeV~20MeV(variable) • Beam Emittance: 3000mm·mrad(normalized) (if possible, 6000mm·mrad for margin) • Aperture :>45mm(Horizontal and vertical) • Fast injection(Kicker +Septum) • Kicker rise time :<20ns

  3. Beam injection in EMMA ring… • In EMMA, to study the beam dynamics of non-scaling FFAG and resonance crossing acceleration, the injection and extraction energy should be varied to arbitrary energy (if possible) in the range of 10MeV~20MeV. • The requirements of injection and extraction are similar (if possible,) the same scheme should be adopted. • The item to be investigated is whether sufficient orbit separation at the septum can be generated with kickers of realistic specifications (Orbit downstream of the septum can not be studied without realistic 3d field map)

  4. Scheme & Specifications • Kicker aperture: 45(H)  45mm(V):window frame type • Kicker length:100mm Bare inductance ~130nH • Kicker field strength: ~730gauss/20kV (20ns rise time, 150nH inductance) • Direction: horizontal, from outside • Serial straight sections for kicker and septum Tune variation: 0.38~0.18/cell

  5. Tracking studies • Tracking code : ZGOUBI(Sacley Group,F.Meot) • Magnet Parameter: From S.Berg • Fringing field : Enge type fall off 2in 2out C0=0.1455, C1=2.2670, C2=-0.6395 C3=1.1558, C4=C5=0.

  6. Tracking(without fringing field) Kicked beam Physical aperture Physical aperture Kicked beam Circulating beam Septum can be installed here Circulating beam 15MeV 10MeV Kicker Filed: 1k gauss (30kV) Beam Emittance:6000πmm·mrad(norm.) Physical aperture Kicked beam Observed here Circulating beam 20MeV

  7. 4D tracking with fringing field(horizontal, 1 kicker) Initial emittance: 3000 mm·mrad.(normalized) Physical aperture 10MeV(H) 20MeV(H) 15MeV(H) 15MeV(V) 20MeV(V) 10MeV(V) Kicker: 1kgauss Kicker: 0.6kgauss Kicker: 0.6kgauss

  8. Operation Point Dependence • EMMA ring will be operated in various operational points. Injection and extraction scheme should be accomodated to various operational points • What to be checked are (1) operational point dependence of orbit separation (2) Influence of fringing field in various operational points

  9. Operation Points • As typical operating points, 4 operation points were checked(061206a,8a,8b,9c) • Horizontal tune ranges 0.1 ~ 0.4

  10. Operation Points Dependence(Tracking result) Chamber wall 1 kicker: 0.6kgauss 10cm long 10MeV =3mm·mrad(norm.) 15MeV Sharp edge field X’(mrad) 20MeV kicked beam X(mm) 061206a 061208a 061209c circulating beam

  11. Operation Points Dependence(Tracking result #2) • For 4 operation points(061206a,8a,8b,9c), sufficient orbit separation at septum can be obtained with single kicker(max field 0.7kgauss, 10cm long) • The deformation of kicked beam is still a serious problem in every operation point. ( In the tracking with fringing field in current setup, the field expansion in large amplitude in ZGOUBI has problems. The tracking with 3D field map is required.)

  12. Septum Specifications… 2 options… (1) beam kicked by septum traverses QD and QF Relatively smaller septum field and momentum dispersion. Beam traverses non-quadrupole field (2) beam is bent 90 by septum  orbit after septum can be well-predicted, relatively larger septum field and momentum dispersion * For option 2(90degree bending), the required septum field ~5.4kgauss(septum length:10cm)

  13. Summary • If 1kgauss kicker is available(for 20ns rise time, max HV:30kV), injection(extraction) from 10MeV to 20MeV with one kicker and septum is possible. • Beam shape is very sensitive to the distribution of fringing field. Realisitic field distribution with 3D modeling is crucially important. • Beam injection in 4 typical operation points was investigated and found to be feasible • Influence of fringing field needs detailed study

  14. Summary of specifications • Kicker rise time : 20ns Max field : 1kgauss(possibly ~0.8kgauss) (Max HV: 30kV) length : 10cm aperture : 45mm(H)45mm(V) • Septum(90 BEND) Max field : 5.4 kgauss length : 10cm aperture : 45mm(H)45mm(V)

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