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Slow extraction from PS2. Preliminary design aspects. Prim. MTEBKT. MTEBK. 2 nd sec. B3. B1. B5. B4. B2. InjK. InjS. MS2. MS1. ES. DuK. ExtK. BD+1 st sec. Normalization. Normalized dispersion ( N = normalized )
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Slow extraction from PS2 Preliminary design aspects M. Gyr, TE/ABT/BTP
Prim MTEBKT MTEBK 2nd sec B3 B1 B5 B4 B2 InjK InjS MS2 MS1 ES DuK ExtK BD+1st sec M. Gyr, TE/ABT/BTP
Normalization • Normalized dispersion( N = normalized ) • Normalized emittance (PS2: N = 15µm)(i.e.scaled withenergy) • Emittance in normalized phase space • Beam size (area in phase space): • Normalized beam size (stable area): In the program, the emittance in the normalized phase space has to be input instead of the stable phase space area (the factor is dealt with inside the code) M. Gyr, TE/ABT/BTP
x´ x´ x x x´ x´ x x M. Gyr, TE/ABT/BTP
Parameters for separatrix Choice of p and Q such that: (Qres-Qo)·(Qres-Q) > 0 i.e. resonance approach from below or above doesn't change ! Closed orbit and lens strength for off-momentum particles: M. Gyr, TE/ABT/BTP
Stable area & fixed point M. Gyr, TE/ABT/BTP
Machine parameters Qo = 13.32 Sextupole locations M. Gyr, TE/ABT/BTP
48.7 mm ES Separatrices at the ES M. Gyr, TE/ABT/BTP
Aperture requirements for extraction Envelope for a max. normalized separatrix amplitude of 50 mm (scaled with ; N= 60 m) including Dx and orbit etc. M. Gyr, TE/ABT/BTP
Required aperture for extraction compared with machine aperture Separartrix envelope and 65 mm scaled aperture over one arc and LSS M. Gyr, TE/ABT/BTP
Sextupole strengths + lengths Withnormalized Ks=.0037 mm-1, N = 60 m and S = 20.3 m one finds: Kick strength of a multipole of order n: LSE of SPS (l = .7m, Ø = 120mm, Imax = 395A) : @ 50 GeV: k3 = .995 m-2(~ 3 times the required strength !) M. Gyr, TE/ABT/BTP
Beam envelope in extraction channel MS1 MS2 ES QMA M. Gyr, TE/ABT/BTP
Enlarged QMAwith coil window Coil window needs to be larger than in the QFA/QDA of the SPS since extracted beam Passes through 2 magnets M. Gyr, TE/ABT/BTP
Electrostatic septum Angular deflection k of a particle with momentum p and relativistic speed c in an electrostatic field E of length L : For high momentum particles (1) and for one ZS-unit, having an electric field length of L = 3m (length of the cathode), the conversion factor is : (Emax = 100 kV/cm) M. Gyr, TE/ABT/BTP
Magnetic septa Angular deflection k of a particle traversing a magnetic field B is proportional to the integrated field strength B·d and inversely proportional to the momentum p. The necessary current in the magnet for a demanded deflection is given by Assuming that the MS1 and MS2 have the same type of coils as the MST and MSE (but longer cores) the following values are found by scaling : M. Gyr, TE/ABT/BTP
Minimum real septum positions Magnetic bumpers The 5 Bumpers are assumed to be of MPSH, MPLH and MPNH-type as in the SPS M. Gyr, TE/ABT/BTP
Required deflections Momentum (GeV/c): 50.9 ZS-Strength (mrad): 0.82466130 MS1-Strength (mrad): 3.59243065 MS2-Strength (mrad): 21.64154794 Bumper-Strengths (mrad): MBP5A : -0.77039136 MBP4B : 1.17497994 MBP3B : 0.09878870 MBP2B : 2.12425185 MBP1B : -1.65216901 M. Gyr, TE/ABT/BTP
Required currents ES-Field (kV/cm): 70.00000 MS1-Current (Amp): 3403.10237 MS2-Current (Amp): 10250.49754 Bumper-Currents (Amp): MBP5A : -54.30266854 MBP4B : 42.24826035 MBP3B : 3.80890182 MBP2B : 76.38083163 MBP1B : -116.45663534 M. Gyr, TE/ABT/BTP
Conclusions • Slow extraction feasible with this layout and the proposed machine aperture • Lenses, bumpers & septa strong enough r • reserve for CO-correction with bumpers! • Suppression of 3rd bumper ? • Enlarged Quadrupoles with wider window than in the SPS • Thin septum MS1 may be suppressed (?) M. Gyr, TE/ABT/BTP