PIP-II Superconducting RF Linac Status and Challenges" Leonardo Ristori! ICEC-ICMC Conference, New Delhi!!
Outline" PIP-II Mission & Strategy! PIP-II SRF Linac Overview! Technical Risk & Mitigation! Indian Institutions & Fermilab Collaboration! PXIE R&D Plan at Fermilab! Focus on PXIE SSR1 Cryomodule! Cryomodule Features! Processing of Superconducting Resonators! Cold Tests of Resonators! SSR1 Cryomodule Schedule! Summary! 2!
Proton Improvement Plan II (PIP-II) mission " q Par2cle Physics Project Priori2za2on Panel (P5) Science Drivers: " Use the Higgs Boson as a New Tool for Discovery! Pursue the Physics Associated with Neutrino Mass! Identify the New Physics of Dark Matter! Understand Cosmic Acceleration : Dark Energy and Inflation! Explore the Unknown : New Particles, Interactions, and Physical Principles! q Proton Improvement Plan II (PIP-II): PIP-II endorsed by P5 as a key element in the U.S. neutrino program R&D program underway (PXIE & IIFC CollaboraDon) 3!
PIP II Superconducting RF Linac" 800-MeV superconducdng linac, constructed of CW-capable components, operated inidally in pulsed mode 4!
Proton Improvement Plan II (PIP-II) mission and strategy Increase Main Injector power!!from 700 kw (NOvA) to >1 MW (LBNF)!!in the energy range 60 120 GeV! Increase Booster power from 80 to 160 kw! 8 GeV program: SBNE,! PIP-II Currently in CD-0 (13 Nov 2015)! Roadmap for CD-3 in 2019-2020! Construction phase is 5 years: 2019-23! Goal is 1 MW in 2024! 5!
The Linac Reference Design Section Freq Energy (MeV) Cav/mag/CM Type RFQ 162.5 0.03-2.1 HWR (β opt =0.11) 162.5 2.1-10.3 8/8/1 HWR, solenoid SSR1 (β opt =0.22) 325 10.3-35 16/8/ 2 SSR, solenoid SSR2 (β opt =0.47) 325 35-185 35/21/7 SSR, solenoid LB 650 (β g =0.61) 650 185-500 33/22/11 5-cell elliptical, doublet* HB 650 (β g =0.92) 650 500-800 24/8/4 5-cell elliptical, doublet* *Warm doublets external to cryomodules All components CW-capable 6!
HWR, SSR1, HB650 Cryomodules" 7!
SRF Accelerating Structures (aka SRF Cavities)" 8!
Main challenges and technical risks " Future upgrades to CW operation! Higher cryo-losses high Q 0 is desired! High-Q 0 program was initiated and is running successfully! Low beam loading narrow bandwidth! Pulsed regime Lorentz Force Detune (LFD)! Resonance Control program is underway in order to mitigate both microphonics and LFD! CW regime microphonics! Passive mitigation of cavity detuning improvement of cavity stability is underway! High-Order Modes! Dampers needed?! Detailed HOM analysis is performed no need for dampers! 9!
Passive Control: Sensitivity to He bath pressure (df/dp)" Cavity walls deform proportionally to the increment of pressure in the liquid Helium.! Changes in the cavity RF volume produce frequency shifts that can be positive or negative depending on the shape of deformation! Slater s rule:! df/dp > 0 df/dp < 0 High H P 0 + Δ P + Δ P High E +Δ f -Δ f -ΔV -ΔV 10!
SSR1 Cavities: pressure sensitivity" SSR1 cavities were designed to have very low sensitivity to helium pressure fluctuations.! The niobium cavity was physically coupled to the helium vessel which was designed in such way that the overall deformed shape produces a very low df/dp within the requirements : df/dp 25 Hz/Torr! " df/dp [Hz/Torr]! S106! S107! S108! S109! S110! S111! S112! S113! S114! D. Passarelli Bare cavity (with transition ring)! -564! -561! -553.5"-555.1"-568.8"-525.8"-524.6"-544.7"-557.2" Measured! With He Vessel! (without Tuner)! 8! 8! -1.2" 5.4" 7.9" 2.7" 9.0" 6.3" 10" Fully integrated! 4*! 4! 0*! 2*! 4*! 2*! 5*! 3*! 5*! * Not measured yet (best guess)! 11!
Resonance Control R&D program " Piezo feedback has successfully stabilized the resonance with high precision in CW to negligible levels (11 mhz RMS)! Ponderomotive instability has been successfully mitigated using piezo feedforward tied to the square of the gradient during both CW and pulsed operation! Adaptive feedforward has successfully suppressed detuning from deterministic sources of detuning! Techniques for fully characterizing the tunercavity-waveguide system automatically have been developed and used successfully! No compensadon Over compensadon (W. Schappert, Yu. Pischalnikov, J. Holzbauer) 12!
High Q0 R&D program" Results highlights 120C bake versus N doping Q~ 7e10 at 2K, 17 MV/m world record at this frequency!! Applying N doping to 650 MHz (beta=0.9) leads to double Q compared to 120C bake (standard surface treatment ILC/XFEL)!! A. Grassellino 13!
Indian Institutions & Fermilab Collaboration" http://iifc.fnal.gov! Agreement between:! India, Department of Atomic Energy (DAE)! USA, Department of Energy (DOE)! Collaboration on:! Design, Research, Development and Construction of High Intensity Superconducting Radio Frequency Linear Proton Accelerators (HISPA)! In-kind contributions (knowledge transfer and hardware) to eachother s accelerator programs! Indian Spallation Neutron Source at RRCAT! PATHIPA Program at BARC! PIP-II at Fermilab! 14!
IIFC Joint R&D Goals for 2018" Development and High Power Testing of SRF structures:! 325 MHz Single Spoke Resonators (SSR1, SSR2)! 650 MHz 5-cell Elliptical Cavities (LB650, HB650)! Development and testing with beam of:! 1 SSR1 cryomodule! 1 HB650 cryomodule! Development of associated components & facilities:! RF Power Couplers! Frequency Tuners! Magnets! Solid State Power Amplifiers! Cavity Test Facilities! At the end of R&D program (2018), IIFC institutions in position to take up construction of projects for its respective domestic programs! 15!
PIP-II Injector Experiment ( PXIE R&D Program) "" 30 kev H- 5 ma from 1 µs to DC 2.1 MeV, CW 4-vane, 4- module. Designed and manufactured at LBNL. ~10 m, with bunch-bybunch selecdon. Magnets are being made by BARC, India. 162.5 MHz, 10 MeV. Designed and being manufactured at ANL. 325 MHz, 25 MeV. Designed and manuf. at Fermilab. + IIFC contrib. DiagnosDcs and 2 ma CW, 25 MeV dump. 16!
SSR1 Cryomodule R&D Goals" Validate new spoke cavity cryomodule design concepts! Room temperature strongback! Individual support posts to control axial motion! Conduction cooled magnet current leads (not new, but new to us)! Single-window coaxial input coupler! Integral beam instrumentation! Determine the practicality of tuner access ports! Validate alignment concepts! Gain experience with the required alignment tolerances! Verify alignment stability during cooldown! Verify static and dynamic heat load estimates! Clean-Room assembly! Gain experience with strings of spoke cavities, solenoids, and beam instrumentation, e.g. cleanroom operations, shipping and handling, etc.! Cryomodule assembly! Gain experience with the overall assembly of individual components, cavity strings, cold mass assembly, and final assembly in the vacuum vessel.! 17! L. Ristori PIP-II SRF Linac!
SSR1 Cryomodule" Room-temperature strongback structure maintains cavity spacing ader cool-down. Each element has own support post. 18!
SSR1 String Assembly: design features" 20mm! Edge-welded bellows assembly! Al-diamond seals! SiBr set screws! 316L stainless nuts and washers! Interconnection cavity-cavity" SSR1" Type A" SSR1 Type B" SSR1" Type A" SSR1 Type B" SSR1" Type A" SSR1 Type B" SSR1" Type A" SSR1 Type B" Gate Valve" Coupler (cold-end)" Solenoid" BPM" Gate Valve" Interconnection cavity-magnet- BPM-cavity" Hydro-formed bellows assemblies! Al-diamond seals! SiBr set screws! 316L stainless nuts and washers! 19!
SSR1 String Assembly: Beam-line vacuum" High vacuum level (< 5E-5 Torr) is needed inside the beam line volume before the introduction of liquid helium in less than 12 hours.! Ø Measurements (very conservative conditions)! Pressure Gauges" Ultimate pressure is below 5e-5 Torr! Vacuum Manifold is not needed!" Vacuum Pump" Ø Vacuum simulation (best scenario)! The high-vacuum level at room temperature can be achieved pumping down by the beam ports only. Furthermore, simulations performed on the entire string with clean components show that the achievable pressure would be of 7E 8 Torr pumping from both ends.! UlDmate pressure is below 1e-7 Torr High-vacuum Simulations and Measurements on the SSR1 Cryomodule Beam-line, D. Passarelli et al., Proceedings of SRF2015, Whistler, BC, Canada! 20!
Processing/Testing steps (ANL, FNAL)" 1 Bare Cavity Inspection Visual, Dimensional, Vacuum, RF 2 US cleaning and rinse 3 BCP 120-150 µm (flip half-way) 4 High-Pressure Rinse 5 Hydrogen Degassing 600 C, 10 h 6 RF Tuning ANL ANL 7 BCP 20-30 µm 8 HPR (horiz + vert) ANL 9 Clean Room Assembly 10 Low Tem Bake 120 C, 48 h 11 Vertical Test @ 2K 12 Helium Vessel Welding 13 US cleaning 14 BCP 20-30 µm Bare cavity BCP setup 15 HPR 16 Clean Room Assembly FNAL High-Temp Oven (<1000 C) FNAL 17 Low Temp Bake 120 C, 48 h 18 Horizontal Test @ 2K 19 Ready for String Assembly Low-Temp Ovens (<300 C) 21 L. Ristori PIP-II SRF Linac
Vertical Tests of 10 SSR1 Cavities (bare)" 10 A. Sukhanov 10 10 10, 0 Q 1-1 10-2 10 Q - solid marker, X-ray - empty marker 0 S1H-NR-105: June 27, 2012 S1H-NR-107: July 30, 2012 S1H-NR-109: November 14, 2012 S1H-NR-108: January 16, 2013 S1H-NR-113: March 7, 2013 S1H-NR-110: April 26, 2013 S1H-NR-112: May 31, 2013 S1H-NR-114: October 2, 2013 S1H-NR-111: October 8, 2013 S1H-NR-106: February 19, 2015 PIP-II specifications 10 0 2 4 6 8 10 12 14 16 18 20 22 E acc =V acc /βλ, MV/m 0 10 20 30 40 50 60 70 80 E pk, MV/m 0 20 40 60 80 100 120 B pk, mt 1-1 10-2 Radiation, mr/h 22!
Status: SSR1 Cavities from IUAC S103, S104 " Two SSR1 cavities were received from IUAC, chemically processed and cold-tested at Fermilab. The summary plot shows performance of cavity S1F-IU-104 (magenta) together with other Fermilab cavities. The second cavity was also tested (separate plot) and had field emission. This should not be a problem after jacketing and another pass of light chemistry.! S1F-IU-103 12092015 60 1E10 2K 50 Q 0 1E9 4K PXIE 40 30 20 X-Ray (mr/hr) 10 1E8 0 0 2 4 6 8 10 12 14 16 Eacc(MV/m) Cold Tests of SSR1 Resonators Manufactured by IUAC for the Fermilab PIP-II Project, L. Ristori et. al, SRF15 Conference! 23!
SSR1 325MHz Coupler: Status" Design specifications" Beam power gain per cavity (CW): ~2 kw.! Maximum design power (PIP-II, 5 ma): ~30 kw.! One ceramic window at room temperature.! No external adjustment.! Air cooled center conductor.!! Prototype Couplers" Three prototype couplers successfully tested to 8.5 kw at room temperature. Tested to failure at room temperature -> 47 kw.! One prototype coupler tested in STC at the maximum design power of 30 kw.!! Cold-end assembly! RF test stand! Status of 325 MHz Main Couplers for PXIE, S. Kazakov, Proceedings of LINAC2014, Geneva, Switzerland! 24!
Status: S107 Ice Breaker Fully-Integrated Tests in STC" First jacketed cavity was tested in the STC cryostat! Prototype coupler and prototype tuner installed! Performance of cavity, coupler and tuner were confirmed with a total of 3 tests! Campaign of qualifications for cryomodule to start soon.! Prototype tuner! No degradadon found in comparison of performance of cavity S107 in VTS (black) and STC (red). Prototype coupler! Result of Cold Tests of the Fermilab SSR1 Cavities, A. Sukhanov et al., Proceedings of LINAC2014, Geneva, Switzerland! 25!
SSR1 Cryomodule Schedule " 8 Cavity qualifications May-Nov 2016! Couplers (1 st delivery of 2 units March 15)! Tuners (production design being finalized)! String assembly Aug-Dec 2016! Facilities, Tooling and Procedures (making progress)! Cold Mass Components Procurements Jun-Dec 2016! Cold Mass Assembly Jan-Jun 2017! Cryomodule delivery to PXIE Cave at CMTF Feb 2018" 26! L. Ristori SSR1 CM Engineering & Documentation" 2/25/2016!
Lab 2 Facility Inaugurated!" 27! PIP-II facility for construction of 325/650 MHz cryomodules & preparation of cavities! Class 10 clean-room, String Assembly, High Pressure Rinsing! Water production plant! LN2 outside dewar! 12.5 T Cryomodule Assembly Area! Tech Rooms, Office Spaces! Conference Room! S. Posen YOU ARE HERE Before
Summary" PIP-II at Fermilab has CD-0 approval. R&D phase well under way, construction to begin in 2019 with a goal of 1MW beam in 2024.! Main challenges and technical risks addressed by PXIE R&D program, 25 MeV 2mA beam in 2018! Collaboration with Indian Institutions is of great importance for the success of PIP-II! SSR1 cryomodule contains state of the art features and is in advanced stage of construction! First round of cold tests of SSR1 cavities yielded excellent results, last round of fully-integrated tests to begin imminently! 28!