Vacuum issues concerning the Proton Source and LEBT Salvo Marletta, Luigi Celona, Lorenzo Neri, Franco Chines, David Mascali.

Nomenclature TMP for Turbomolecular Pump PP for Primary Pump Full Range for vacuum gauge Pir For for Foreline Pirani gauge FV for TMP foreline section GDV for Gas Dosing Valve (i.e. the inlet valve for support gas used for space charge compensation) GV for Gate Valve, i.e. line gate valve RGA for Residual Gas Analyis MFC for Mass Flow Controller

Present design of P.S. and LEBT: pumps, gauges and residual gas analyzer Low Energy Beam Transport Line Proton Source Expected Operative Pressures BEAM OFF – Static Vacuum P.S.range 10E-6 mbar LEBTrange 10E-7 mbar BEAM OFF – Gas IN P.S.range 10E-3 mbar LEBTrange 10E-5 mbar 2100 mm 400 mm RFQ (Diaphragm Φ = 6-8 mm; Depth = 10mm

General Vacuum layout

Full Range 1 Full Range 2 Positioning of: n.2 Primary Pumps n. 2 TMP n. 2 Full Range gauges n.2 Pirani n.1 RGA (res. gas analyser) Positioning of: n.2 Primary Pumps n. 2 TMP n. 2 Full Range gauges n.2 Pirani n.1 RGA (res. gas analyser) RGA Present design of P.S. and LEBT: pumps, gauges and residual gas analyzer

Present design of P.S. and LEBT: Pumps characteristics 1 Flange Pumping speed (H2) Pumping speed (N2) Compr. Ratio (H2) Maintenance DN 200CF-F 580 l/s 800 l/s 4 · 10e5 In situ Drag Turbomolecular pump LNS proposal PFEIFFER Hi Pace TURBO PUMP: BENEFITS Ceramic ball bearing on the fore-vacuum side and a permanent magnetic radial bearing on the high vacuum side. Bearing technology does not require electromagnets: long service life with 4 years maintenance. The ball bearing and the operating fluid reservoir can be replaced on site within less than 30 minutes. High Compression ratio and high gas throughput at full rotational speed for H2. Rotation speed variable %. Mounting in any orientation.

Present design of P.S. and LEBT: Pumps characteristics 2 Flange Pumping speed Final Pressure Frequency Converter Maintenance DN 25 ISO-KF 28 m 3 /h 3 · 10e-2 Yes >2 years Primary Pump LNS proposal PRIMARY PUMP ACP 28 : BENEFITS Designed for dust-free and non corrosive gases. Equipped with a gas ballast device to improve pumping of light gases and avoid condensation of vapours. Air cooling: no water supply required Frequency converter: hour meter, remote operation mode (RS-485, dry contacts, Profibus on request), multiple rotational speed selection (power saving, noise reduction, adaptation to application cycle) No particle contamination, thanks to frictionless design: no wearing parts in the pumped gases path Constant performances (Pumping speed, max. and ultimate pressure)

Present design of P.S. and LEBT: Full range gauges Flange Operating Range Inferface Maintenance DN 35 CF-F Atmosphere to 10e- 8 mBar RS485/AnalogIn situ Full Ranges LNS proposal 974 QuadMag™ Cold Cathode/MicroPirani™/Piezo Vacuum Transducer (1x10 -8 to 1500 Torr) BENEFITS The 974 QuadMag™ vacuum transducer combines cold cathode inverted magnetron, MicroPirani™ and Piezo differential vacuum sensor technologies. User serviceable to decrease downtime Both analog and digital communication Optional local display

Present design of P.S. and LEBT: Pirani gauge Flange Operating Range Inferface Maintenance DN 25 ISO-KF Atmosphere to 10°- 5 mBar RS485/AnalogIn situ Pirani LNS proposal 910 DualTrans™ MicroPirani™/Absolute Piezo Vacuum Transducer (1.0x10 -5 to 1500 Torr) BENEFITS 2 sensors in one ultra-compact unit saves space Wide measurement range Gas independent above 10 Torr Optional 3 setpoints with fast response time for reliable process control

Present design of P.S. and LEBT: Residual Gas Analyzer Flange Operating Range Gas Mass Company DN 35 CF-F ≈ 10e-5 mBar AMUany RGA During Vacuum test (especially in the start-up phase) the use of a mass spectrometer is very useful for the analysis of partial pressures due to the different gases in the source/line.

Present design of P.S. and LEBT: Vacuum equipments GDV-2 GDV-1 GDV-3 Gate Valve 2 Gate Valve 1 Positioning of: n.2 Gate Valves for line sectioning n. 3 GDV for gas supply (space charge compensation) N. 1 Mass Flow Controller (for H2 supply) Positioning of: n.2 Gate Valves for line sectioning n. 3 GDV for gas supply (space charge compensation) N. 1 Mass Flow Controller (for H2 supply) MFC

Present design of P.S. and LEBT: Gas Dosing Valves For proton beams featuring I>50 mA space charge effects cannot be neglected: reciprocal coulombian repulsion affects the beam quality (emittance) with a poor coupling to RFQ. Compensation of the positive proton space charge is possible through additional supply of gases (e.g. Ar) in the LEBT: gas ionisation provides compensating electrons to the beam, thus mitigating the emittance growth. Additional gas injection must be ensured along the LEBT in three different points, using suitable Gas Dosing Valves as UDV140-Thermomechanical Gas Dosing Valve

Present design of P.S. and LEBT: Mass Flow Controller FittingFull ScaleInferface 6mm Svagelok5 sccm RS485/Analog MFC: for gas input (H2) in the proton source LNS proposal GE50A General Purpose Multi-gas, Multi-range Elastomer-sealed Mass Flow Controller BENEFITS fast and repeatable response to setpoint throughout the device control range. Typical response times are on the order of 500 milliseconds. 1% of setpoint accuracy on the calibration gas. thermal sensor design for exceptional zero stability Embedded user interface - easily change device range & user gas, monitor & measure performance

Performance (in terms of expected leak rate & outgassing) BEAM OFF Due to copper sealing, expected leak rate is in the range of mbar l/s The manufacturing of the LEBT items (in terms of polishing, specifics of metals employed, workshop manufacturing, etc.) will minimize background outgassing with respect to the H2 gas load during machine’s operations. BEAM ON However, during operations and pulsed beam production outgassing will be affected by (e.g.) the chopped beam impinging on chopper plates and/or diaphragm. Another critical point could be the beam interaction with the iris designed for cutting beam halos. This will require dedicated characterisation of “machine-running” outgassing during the early phase of prototype characterisation at LNS.

Other points Material + welding (mainly related to flanges+tubes+bellows) Materials provided by LNS funds. Welding done by LNS mechanical workshop Sealing technology Metal gasket, except in Foreline piping (viton).

Questions Instrumentation & cabling (in case it won't be provided by ESS) ?? Leak testing procedure and reports ?? (Leak detector could be helpful if provided by ESS)