Beam Screens for Inner Triplet Magnets Upgrade Phase

Beam Screens for Inner Triplet Magnets Upgrade Phase 1 Nicolaas KOS AT/VAC u u u Requirements Proposals Examples of cross-sections Aperture Manufacturing issues LIUWG 14 15 -05 -2008 Nicolaas KOS

Beam Screen - Requirements u u u u Provide sufficient H and V aperture (without rotation) Control gas density in beam tube Non-magnetic (μ < 1. 005) Withstand forces during quench Operation between 5 -20 K Evacuate heat load Only for Q 1 : Absorber to intercept debris from IP LIUWG 14 15 -05 -2008 Nicolaas KOS

Beam Screen - Proposals u u u 2 mm P 506 stainless steel for mechanical stability during quench and low magnetic perm. (μ ≤ 1. 003) Cu layer on inner surface to homogenise the BS temperature and give low impedance ≥ 5 % pumping slot surface 4 laser welded cooling tubes to evacuate heat load (ΔT ≈ 3 K between BS and He at 4 x 1 W/m) Identical BS cross sections in Q 1, Q 2, Q 3 (+D 1) Absorber positioned inside Q 1 beam screen LIUWG 14 15 -05 -2008 Nicolaas KOS

Race Track Design Based on existing beam screen design. Well suited for continuous forming; difficult to press as half shells. LIUWG 14 15 -05 -2008 Nicolaas KOS

Octagonal Design 42º 48º Well suited to press as half shells. Compromise on aperture. LIUWG 14 15 -05 -2008 Nicolaas KOS

Optimised octagonal design 42º 48º Well adapted to press as half shells. Increased aperture compared to octogonal design. LIUWG 14 15 -05 -2008 Nicolaas KOS

Absorber in Q 1 BS – 1 - - BS pumping slots partially masked - Pumping slots to be machined through thick absorber - Absorber weight (8 mm ss) - Total BS weight (l = 10 m) LIUWG 14 15 -05 -2008 18 kg/m 240 kg Nicolaas KOS

Absorber in Q 1 BS – 26. 1 9. 8 40. 1 - BS pumping slots remain accesible - Cu plated P 506 (11 kg/m) or Cu-alloy (13 kg/m) - Machined sections, unit lenghts to be defined - Screwed / brazed onto inner BS surface - RF contacts between sections ? - Half-aperture loss 9. 8 mm compared to Q 2 / Q 3 - Q 1 total beam screen weight 170 kg LIUWG 14 15 -05 -2008 Nicolaas KOS

Optimised octagonal design main dimensions in 119 ID CBore 2. 2 ± 0. 1 16 rows, 50% transparency 5. 1 % 116 ± 0. 5 106 ± 0. 5 114 ± 0. 5 LIUWG 14 15 -05 -2008 Nicolaas KOS

Radial BS size (corner) at RT for given cold bore diameter OV = ID/2 - g - (d+ d) - b * Where: *) OV = nominal vertical beam screen outer half-dimension [mm] ID = nominal cold bore inner diameter [mm] ID = tolerance on cold bore inner diameter [mm] g = minimum radial gap [mm] d = nominal BS support thickness [mm] d = tolerance on BS support thickness [mm] b = tolerance on beam screen outer half-dimension [mm] Vacuum Technical Note 01 -13, EDMS 350449 LIUWG 14 15 -05 -2008 Nicolaas KOS

Half-Aperture (corner) at 5 K for given cold bore diameter AV = 0. 99727(ID/2 - 3 ID/2 - 2 g - d - 3 d - 4 b - w - bss ) * Where: AV = vertical beam screen half-aperture [mm] 0. 99727 = thermal contraction factor for P 506 from 293 K to 5 K ID = nominal cold bore inner diameter [mm] ID = tolerance on cold bore inner diameter [mm] g = minimum gap [mm] d = nominal sliding ring thickness [mm] d = tolerance on the sliding ring thickness [mm] b = tolerance on beam screen outer half-dimension [mm] w = nominal beam screen wall thickness [mm] w = tolerance on beam screen wall thickness [mm] bss = beam screen straightness error [m/m] = longitudinal distance between rings [mm] *) Vacuum Technical Note 01 -13, EDMS 350449 LIUWG 14 15 -05 -2008 Nicolaas KOS

Half-Aperture (corner) at 5 K for given cold bore diameter AV = 0. 99727(ID/2 - 3 ID/2 - 2 g - d - 3 d - 4 b - w - bss ) = 53. 0 AV = beam screen half-aperture between corners [mm] 0. 99727 = thermal contraction factor for P 506 from 293 K to 5 K ID = nominal cold bore inner diameter [mm] ID = tolerance on cold bore inner diameter [mm] g = minimum gap [mm] d = nominal sliding ring thickness [mm] d = tolerance on the sliding ring thickness [mm] b = tolerance on beam screen outer half-dimension [mm] w = nominal beam screen wall thickness [mm] w = tolerance on beam screen wall thickness [mm] bss = beam screen straightness error [m/m] = longitudinal distance between rings [mm] LIUWG 14 15 -05 -2008 119 1. 44 0. 1 0. 4 0. 03 0. 25 2. 075 0. 06 0. 001 400 Nicolaas KOS

Potential gain in half-aperture at zero tolerances AV = 0. 99727(ID/2 - 3 ID/2 - 2 g - d - 3 d - 4 b - w - bss ) Half-aperture gain ID = tolerance on cold bore inner diameter [mm] = 0 + 2. 2 d = tolerance on the sliding ring thickness [mm] = 0 + <0. 1 b = tolerance on beam screen outer half-dimension [mm] = 0 + 1. 0 w = tolerance on beam screen wall thickness [mm] = 0 + <0. 1 bss = beam screen straightness error [m/m] = 0 + 0. 4 LIUWG 14 15 -05 -2008 Nicolaas KOS

Potential gain in half-aperture for pre-measured cold bore ID AV = 0. 99727(ID/2 - 3 ID/2 - 2 g - d - 3 d - 4 b - w - bss ) dif = measured minimum ID – specified minimum ID ID’ = ID + dif/2 (assuming specified maximum ID unchanged) ΔID’ = ΔID – dif/2 half-aperture increase = dif/4 + 3 dif/4 = dif Example : Specified minimum ID = 119 – 1. 44 = 117. 56 mm Measured minimum ID = 118 mm Half-aperture increase = dif = 118 – 117. 56 = 0. 44 mm !!!! Requires availablility of all cold bores before finalising the BS design !!!! LIUWG 14 15 -05 -2008 Nicolaas KOS

Heat load BS cool. tubes W/m BS supports 0. 05 W/m CW-transition : 5 W radiative 3 W conductive + 8 W total BS cool. tubes W/m BS supports 0. 05 W/m Q 1 Q 2 B Q 2 A 10 m Electr. cloud 1 W/m Debris W/m + --------------- Total W/m BS cool. tubes W/m BS supports 0. 05 W/m Electr. cloud 1 W/m Debris W/m + --------------- Total W/m 10 m Electr. cloud 1 W/m Debris W/m + --------------- Total W/m BS cool. tubes W/m BS supports 0. 05 W/m Q 3 CW-transition : 5 W radiative 3 W conductive + 8 W total 10 m Electr. cloud 1 W/m Debris W/m + --------------- Total W/m ΔT ~ 3 K between beam screen inner surface and He for 1 W/m per cooling tube Support heat load estimated 10 x the value for arc beam screens LIUWG 14 15 -05 -2008 Nicolaas KOS

Manufacturing Issues u u u u Lead time for P 506 steel strip >12 months Co-laminator (Heraeus, D) not interested (!/? ) Former/welder (Butting, D) not interested Octagonal design is more adapted to be built from pressed half shells than race track design Cu-layer can be applied by means of electroplating (higher RRR, thinner layer) Absorber attachment+thermalisation Finalisation of input parameters : CB diameter, magnet lengths and interconnect lengths LIUWG 14 15 -05 -2008 Nicolaas KOS