ZQNA Electrostatic Quadrupoles for ELENA Transfer Lines 1

ZQNA Electrostatic Quadrupoles for ELENA Transfer Lines 1. 2. 3. 4. 5. Conceptual design Performance Engineering details Interfaces Production planning D. Barna, W. Bartmann, P. Moyret, R. Ostojic, J-F. Poncet IIC, 31 July 2014

Documentation Engineering Specification: Mechanical drawings in CDD under “AD_ZQNA%”.

Functional requirements - 1 Strength – Quadrupoles: – Correctors: Aperture 6 m-1 (100 ke. V antiproton beam) 10 mrad (100 ke. V antiproton beam) – Separation between electrodes: at least 60 mm mechanical aperture – All other components of the assembly (e. g. flanges) should have larger diameter. Field homogeneity – “Good field” region: radius 20 mm – Relative change in the good field region: < 10 -3 Dimensions – Distances between electrodes and ground: greater than 10 mm – Aperture limiting electrodes (field clamps) to be included to minimize field leakage and coupling between electrodes. – The overall length and diameter of the assembly should be as small as feasible.

Functional requirements - 2 Electrical – Conservative values of the nominal design voltages should be chosen (~ 5 k. V for the quadrupoles, ~2 k. V for the correctors). – All non-active electrodes must be properly grounded. – Operation in quasi-static mode: no requirement on the switching time. Powering – The quadrupoles are powered either individually or as a string. The polarity of the quadrupole is fixed. If necessary, the changes of polarity will be made by modifications in the external circuit. The operating range is from nominal voltage to as low as 100 V. – The correctors must be powered individually, with variable voltage and polarity. – The voltage stability: 10 -4 of the nominal value for the quadrupoles. 10 -3 for the correctors. Alignment tolerances – The changes in the beam orbit due to assembly misalignments must be small compared to the beam size in the transfer lines. Vacuum – The assembly must be compatible with the vacuum requirements of the beam lines and must be compatible with bakeout up to 250 o. C. Interlocks – The power supplies must be interlocked with the vacuum system in each vacuum sector, and must be short-circuit proof to avoid damage in case of a rapid vacuum loss.

Conceptual design • Standard electrostatic quadrupole assembly (ZQNA): – – • • two quadrupoles one horizontal and one vertical corrector common vacuum chamber used in all locations, 60 units in total. Quadrupoles powered independently with a focusing or defocusing polarity (or with the same polarity if more strength needed). H/V correctors powered independently in a bipolar arrangement. Electrode assembly mounted on a reference flange, which also serves for rigid attachment of a BPM. Assembly fully symmetric around the vertical axis and can be mounted with the fixed flange (BPM) on the left or right.

Main parameters Quadrupole-1 Correctors Quadrupole-2 Aperture 60 mm Nominal strength 6 m-1 10 mrad 6 m-1 12 k. V 6 k. V 12 k. V (± 6 k. V wrt ground) (± 3 k. V wrt ground) (± 6 k. V wrt ground) 10 mm Electrode length 100 mm 37+37 mm 100 mm Polarity F or D H and V F or D Capacitance 104 p. F (tbc) 10 -4 10 -3 10 -4 2 -pin SHV-10 k. V 4 -pin SHV-10 k. V 2 -pin SHV-10 k. V on DN 35 CF flange Nominal voltage Min electrode-ground distance Required Voltage stability HV feedthroughs Length (flange-to-flange) 390 mm Vac chamber outer dia. 204 mm Upstream flange DN 200 CF (fixed) Downstream flange DN 200 CF (rotatable) Mass 30 kg

Performance • Quadrupoles – – Strength Field homogeneity Field perturbations from connections Electrical circuit • Correctors – Strength – Field homogeneity – Electrical circuit Leff = 108 mm, Vmax=± 6 k. V Quad-like shape of aperture plate OK 104 p. F (tbc) Leff = 55 mm, Vmax =± 3 k. V Decoupled and rounded H/V electrodes (tbc)

Engineering details • • • Vacuum vessel Electrodes and supporting system HV connectors Assembly support Interfaces

Vacuum vessel • AISI 316 L body, 2 mm wall, 204 mm OD. • AISI 316 LN, DN 200 CF flanges (fixed and rotatable). • Other elements in AISI 304 L. • Inside wall NEG coated.

Electrodes • All materials: AISI 316 L, without NEG coating. • All electrodes supported off four rails with insulator blocks made of alumina 12 mm high.

Electrode support • • • Four rails provide precise positioning of the electrodes with respect to the assembly axis. The rails are connected to the DN 200 CF flanges through flange inserts. On the upstream side (fixed DN 200 CF flange), the fixation is rigid. On the downstream side (rotatable DN 200 CF flange), the rails are supported using sliding bolts, which allow thermal expansion of the assembly during bakeout.

HV connectors • • HV feedthroughs with spring loaded pins. Two/four SHV feedtroughs for quadrupole/corrector connections on DN 35 CF flanges. Compatible with bakeout to 250 C. One quote received. Waiting for response of other (potentially cheaper) provider for the 4 -feedthrough flange.

Assembly support • • Four support blocks for connection to the alignment table. Clearance between the HV connectors and the alignment table at least 200 mm. Appropriate features on the table allow controlled movements of the assembly during thermal expansion (bakeout). The alignment table allows horizontal, vertical and longitudinal alignment of the assembly of ± 20 mm, and provides longitudinal fixed point counteracting vacuum forces.

Interfaces 5 4 1) Beam vacuum system: • two DN 200 CF flanges, fixed on the upstream side (1 a), and rotating on the downstream side (1 b). 2) Alignment table: • two support blocks upstream side, two support blocks downstream side. 3) HV powering cables: • two 2 -pin SHV feedthroughs, • one 4 -pin SHV feedthrough. 4) Alignment: • two target holders, one on the upstream side and one on the downstream side. 5) Handling tools: • four M 10 threads. 1 a 1 b 2 3

Production planning Requested availability – Phase-I installation: • 10 ZQNA assemblies by June 2015; – Phase-II installation: • 50 ZQNA assemblies by Dec 2016;

Production planning –EN/MME 12 units 21 May 2015 48 units 24 Nov 2015

Next steps … • Complete and approve the Engineering Specification • Complete and approve design file • Issue orders for component fabrication • Prepare Test and Acceptance Procedure – Aug 2014 – Sep 2014 – Nov 2014