Indian Institutions and Fermilab Collaboration on Accelerator for Indian Nuclear Energy Program P. Singh Bhabha Atomic Research Centre Mumbai January 13, 2011

DAE & US Accelerator Laboratories MOUs

RRCAT, Indore February 10, 2009

1. DAE-ACFAP (Apex Committee to Formulate Action Plan)- Dr S. Banerjee- Chairman 2. IC-IIFC (Internal Committee for Indian Institutions & Fermilab Collaboration (IC-IIFC) Bhabha Atomic Research Centre Raja Ramanna Centre for Advanced Technology Variable Energy Cyclotron Centre Inter-University Accelerator Centre Indira Gandhi Centre for Atomic Research R.K. Bhandari Chairman V.C. Sahni Convener P. SinghMember-Secretary

Proton IS 50 keV RFQ 3 MeV DTL 20 MeV DTL/ CCDTL Super- conducting SC Linac 1 GeV 100 MeV Normal Conducting High current injector 20 MeV, 30 mA Scheme for Accelerator Development for ADS Design completed and fabrication is in progress ECR Ion SourceRFQDTL Beginning/End CellCoupling CellElliptical SC Cavity Phase 1 Phase II Phase III

Layout of the 1 GeV Linac ISRFQDTLCCDTLSC Linac 50 keV3 MeV 50 MeV 100 MeV 1 GeV MHz MHz Design Philosophy Match the beam from one structure to the next. Smooth phase advance per metre across all transitions for current independent matching. Avoid instabilities by keeping the zero current phase advance per period in all planes below 90 deg.

Layout of the Project-X Linac ISRFQSSRBeta=0.6 &0.9 Elliptical ILC SC cavities 50 keV2.5 MeV 160 MeV 2 GeV 3 GeV 325 MHz 650 MHz1300 MHz 0.5 GeV

1.BARC: Physics Design (2.5 MeV RFQ CW), RF coupler, RF power amplifiers at 325 MHz, Instrumentation LLRF, BPM, Phase Monitors, CMTS, infrastructure developments, control systems, accelerator simulators 2.IUAC: 325 MHz, β=0.22 and participation in fabrication of beta=0.61 and 0.9 cavities. 3.VECC: 650 MHz, β=0.61, Design studies, prototype developments, Bead pull measurements, cryostat design for 5 cell SCRF cavities 4.RRCAT: Single cell β=1, 1.3 GHz; β = 0.9, 650 MHz; multicell, VTS, HTS, infrastructure development, material development and testing (Nb RRR=100 at NFC), RF cavity characterization, RF power at 650 MHz.

1.IUAC: 325 MHz, beta=0.22 Two Single Spoke Resonators (SSR1) beta=0.22 at 325 MHz, 1.3 GHz single cell, other cavity developments. Take up fabrication of 4 SSR1s Nb part SS jacket (He Vessel) in collaboration with VECC EB Weld two more single-Cell 1.3 GHz cavities EB Weld 7 – Cell, 1.3 GHz Cavity. For 9-Cell cavity modification of EBW table required. Develop parameters for EB Weld of 650 MHz,  = 0.9 cavity and EBW of single cell and 5-Cell

26 October 2010IIFC meeting, RRCAT Half-Spoke in Cu Half-Spoke in Nb Spoke welded

26 October 2010IIFC meeting, RRCAT Rolled Nb shells Set-up for EBW of Shell

Loading arrangement of dies on the 200 Ton Hydraulic Press at RRCAT Blank Loading for Forming Half cups of finally formed parts of cavity Trials to make 1.3 GHz RRCAT

First Indian single cell Nb cavity made by IUAC+RRCAT Team. The cavity half cells were formed at RRCAT & e-beam welding was done at IUAC. Pictures (Oct 2009) below show the proud team members & the cavity.

1.3 GHZ Single Cell

SCRF Science and Technology Programme at RRCAT  Pursuing a comprehensive programme for design & development of SCRF cavities, cryomodules and related infrastructure  Involved in international collaborative programmmes with mutual scientific benefits For any large scale programme of building high energy proton accelerators for ADS/SNS and various other possible applications, it is essential to develop necessary technologies for the various building blocks involved RRCAT

Qualification of Nb Materials for SCRF Cavity Fabrication All cavities fabricated in the same way do not give high gradients and cavity gradients are often way below theoretical maximum ~ 55 MV/m Usual approach is to use high residual resistivity ratio (RRR) for qualification of Nb material for SCRF cavities. However it is found that superconducting properties of Nb may get adversely affected during fabrication and processing of the cavities (e.g. BCP) Devised a different qualification scheme in terms of superconducting critical field and surface conductivity An implication of this qualification scheme is the possibility that use of moderate RRR Nb material may provide high gradients in SCRF cavities [S. B. Roy et al. Superconducting Science and Technology 21, (2008) and 22, (2009)]

Superconducting Properties of Nb Thin Films Nb thin films on Si substrateNb/Cu bilayer on Si substrate ● Nb thin films grown by ion-beam sputtering ● Studies carried out on variation of superconducting properties w.r.t. thickness of the film and their comparison with properties of bulk Nb. Electrical resistivity measurements SampleT c (K) Nb 300 Å2.94 Nb 400 Å3.84 Nb 700 Å4.84 Nb 1000 Å5.04 Nb 300Å / Cu 300 Å5.14 Nb 400Å / Cu 300 Å5.74 Bulk Nb9.2 ● Optimization of grain size of Nb materials, surface/interface roughness in Nb/Cu bilayers, preparation of films by different techniques K Nb 300 Å Nb 300 Å/Cu 300 Å 5.14 K

Indigenous Development of Nb for SCRF Application RRR is ~ 100 Size 300 mm x 2.8 mm thickness Suitable for 1.3 GHz Cavities SC properties acceptable Hardness ~ 100 Hv ( need < 50Hv) Purity / Chemical composition C,O,H,N ~ 125 ppm ( need<32 ppm) Indigenous Niobium sheets & 3.9 GHz formed half cells NFC, Hyderabad Development of material, testing of mechanical properties RRCAT, Indore Electrical, Superconducting properties, Elemental analysis

Indian Institutions’ Fermilab Collaboration SCRF Cavity & Infrastructure Development

Design Simulations of SCRF Cavities Carried out 2-D and 3-D Electromagnetic Simulations of multi-cell β=0.81 cavities at 1.3 GHz. Lorentz Force Detuning (LFD) has been studied. The effect of sag and stiffeners on LFD has been simulated for the 1.3 GHz, β=0.81 cavities. Simulation Results (3D, 9 cell ) Lorentz force only (+50 Hz) Sag + Lorentz force (+188Hz) 2-D and 3-D Electromagnetic Simulations of multi-cell β=0.9 cavities at 650 MHz have been taken up. Lorentz Force Detuning and the effect of sag and stiffeners on LFD for these cavities will also be studied.

Forming Tool Development for SCRF Cavities Developed forming tooling & process for 1.3 GHz,  =1 SCRF cavity (Dec 2008) Recently developed prototype forming dies for 650 MHz,  = 0.9 SCRF cavity (October 2010) Punch Die 120 T Hydraulic Press

Development Work Done on Forming & Machining ●1.3 GHz SCRF cavity Formed Niobium Half cell InspectionForming Machining

Stages of Cavity Manufacturing & In-Process Qualifications Outside iris weldingEquator trimming Frequency measurementMechanical inspectionFinal equator welding

● Mechanical measurement ● RF measurement ( 300 K & 77K) ● Vacuum leak qualification ( 300 K & 77K) Prototype 1.3 GHz Single-Cell Cavities to Fermilab The two prototypes single-cell 1.3 GHz cavities were subjected to various qualification procedures The cavities were dispatched to Fermilab for processing and testing at 2K for performance evaluation

Indian Single-Cell SCRF Cavity: Processing & Testing at Fermilab and ANL Electro-polishing at ANL Cavity connection vacuum & RF The two prototype single-cell cavities underwent a series of processing stages before finally tested at 2 K Centrifugal barrel polishing at FNAL Electro-polishingCentrifugal barrel polishing High pressure rinsingHeat treatment

The Q v/s E plot of the 2K test of the prototype single-cell superconducting cavity "TE1CAT002" at Fermilab Acceleration gradient achieved: 21 MV/m Performance Testing of Single Cell Niobium Cavity at 2K Cavity mounted on the VTS insert Q0Q0 Q value of 1.5 E+10

Moving Towards 650 MHz  = 0.9 SCRF Cavity Work Plan Process improvement 1.3 GHz  = 1 single-cell cavity (2 Nos.) Capacity building 1.3 GHz  = 1 multi-cell cavity 650 MHz  = 0.9 cavity Single-cell cavity: Q4 – 2011 First 5-cell cavity : Q4 – 2012 (Q1–2013) spare, 5-cell cavities : Q2 – 2014

Infrastructure installed Electro-polishing setup Centrifugal barrel polishing machine High pressure rinsing Cavity forming facility Infrastructure for SCRF Cavity Development Electro-polishing setup Cavity forming facility Centrifugal barrel polishing machine High pressure rinsing Set up

Infrastructural Work In Progress Building expected to be ready by mid Infrastructure being set up Clean room (class to 10) Electron beam welding machine High vacuum annealing furnace Cavity machining facilities CMM, SIMS etc Building under construction (area 70m x 20m)

●A VTS-2 has been designed in collaboration with Fermilab for testing of the following cavities at 2 K : Development of Vertical Test Stand ● RF and DAQ for VTS underway, Building under construction ● Commissioning at RRCAT December 2011 Vacuum vessel Liquid Helium Vessel 80K Shield 2K Magnetic Shield 3-D Models of VTS-2 Vessels  Single & multi-cell SCRF cavities  Single spoke resonator cavity 325 MHz  Triple spoke resonator cavity 325 MHz  Two VTS cryostats for Fermilab and one for RRCAT are under fabrication by a US vendor under joint supervision

Design and development work of a horizontal test stand has been taken up Horizontal Test Stand (HTS-2) Functional requirements Capability to test two dressed cavities at a time but separately. Testing of both 650 MHz and 1.3 GHz cavities. Throughput of 4 cavities in 6 weeks. 3-D Model Completed in UGNX-4 Constructional Details Vessel Diameter: 46 inches Thermal shields for 80 K and for 5- 8 K

Indian Institutions’ Fermilab Collaboration Cryo-Engineering for SCRF Applications

650 MHz SCRF cavity- under design & fab Helium vessel and tuner- to be fabricated Cavity support system & cryogenic support post - under prototyping Thermal shield - under designing Vacuum vessel - under designing Cross-section view Design of 650 MHz Cryomodule Cryomodule sub-systems ● 3-D model completed in UGNX-4

Laser Welding of Cavity Support System SCRF cavity support system in a cryomodule can be simplified by laser welding of SS hangers of the cavity and incorporating a C-T joint. Post-welding distortion:6 microns Laser welding trials were carried out using indigenously developed Nd-YAG laser. Joint’s strength:9 Tonnes

Indian Institutions’ Fermilab Collaboration RF Systems for SCRF Applications

Frequency & Q-factor Measurements RF Characterization of Prototype SCRF Cavity Frequency TE1CAT001 TE1CAT002 FNAL (23 C) RRCAT (27 C) 'Q' factor FNAL (23 C) RRCAT (27 C)

Solid State Amplifier Development at 650 MHz 8kW Amplifier Scheme30kW Amplifier Scheme We have taken up development of 30 kW CW 650 MHz solid state amplifiers for energizing SCRF cavities 32 Nos. of 270 W RF modules are used with suitable combiners and dividers to make a 8 kW RF amplifier module. Four such modules will be combined to obtain 30 kW RF power output. N= Driver 270W modules + RF Generator N=4 30 kW RF Generator Driver 270W module 8 kW Units + + +

Development of RF Components at 650 MHz Several RF components have already been developed and tested for 650 MHz operation 200 W Amplifier Module20W Low Power Driver Coaxial Transitions 2-way 15kW Power Combiner 30 kW RF Dummy Load 4kW & 1 kW Coaxial Directional Couplers

Length of a half-cell of the cavity = L/2 =70.35 mm. Iris radius = R iris = 48 mm. Dome (equator) radius = D/2 = mm. Equator ellipse ratio = A/B = 54 mm/58 mm. Iris ellipse ratio = a/b = 13.5 mm. /27 mm. Frequency: 650 MHz E-field profile along the axis

Bead-pull measurement -- special technique adopted Using Phase-shift technique instead of frequency-shift In manufacturing or tuning multi-cell cavity, it is required to investigate the field profile inside the cavity The Field can be sampled by introducing a perturbing object and measuring its change in f 0 The object must be very small so that the field does not vary significantly over its largest linear dimension: it is a perturbation method Phase deviation is much easier to observe than frequency change especially for small perturbation. PHASE (Degrees)IMPEDANCE

Cryostat with vertical and horizontal cavity

High power RF Source development IOT based RF Amplifier, 60KWatt at MHz Compared to klystrons, IOTs exhibits very interesting characteristics in terms of efficiency (> 65% is usually reached), linearity and compactness. operating at MHz, with powers up to 60 kW CW, compatible with our requirement. We have selected TH 793 IOT for MHz and also for 650 MHz operation Maintenance is simpler -- replacement of the tube only IOT can be re-gunned twice, at about 60% cost of a new IOT Output RF cavities are external to tube. Inductive Output Tube (IOT)- based high power RF source

BARC: Technical Physics Division Solid State Amplifiers at 325 MHz 1 kW ( 2 nos.) and 5 kW ( 1 No.) Solid-state amplifiers Specifications : Center frequency : 325 MHz Bandwidth (3 dB) : 10 MHz Power output (1 dB), CW : 1 kW and 5 kW Gain (1 dB), minimum : 50 dB Gain Stability : +/-0.5 dB Stability : Un conditionally Stable Cooling : Water Cooled Harmonics & Spurious : <30 dBc Efficiency (Total) : > 50% Gain Stabilization with in +/- 0.5 dB 1 kW solid state module under testing

BARC: LEHIPA Development of 50 kW Coaxial Coupler Coaxial coupler connected to RFQ Cavity Alumina tubes metallized in BARC First RF window prototype after vacuum brazing RFCouper prototype being tested for vacuum Coaxial adapters under RF Chracterization 350 MHz RF cavity developed for Coupler conditioning

Ridge waveguide coupler (250 kW) Simulation Model of ridge waveguide based iris coupler 3D Model of waveguide based iris coupler

BARC: Electronics Division IIFC for Instrumentation Following Systems have been identified for Collaboration Low Level RF Control for the control of phase, frequency and amplitude of the RF field in the Cavity Beam Position Monitor Position of Bunched Beam RF protection Interlock Part of machine protection system - prevents power mismatch, sparks, over-voltages, etc. in the high power RF distribution system between klystron and cavity input coupler.

Mode of Working BPM will be designed and tested at Fermilab CDM is designing a cryomodule TPD is designing RF Power System The LLRF control and the RF Protection Interlock System can be tested using the cryomodule set up at CDM. The required control software will be developed.

CDM (BARC) is proposed to be involved in Development of Cryo-Module Test Stands (CMTS) 2 nos. for Fermi Lab Cryo-Module Test stands (CMTS) are required for functional testing of two types of Cryo- Modules. CMTS provides the necessary facilities for maintaining the 2K temp around the SCRF Cavities, which are held in particle free UHV condition inside a Cryo-module.

CMTS consists of following five sub-assemblies: (a)Feed box with transfer lines. (b)Feed Cap with transfer lines. (c)End cap with transfer lines. (d)Transfer lines (e)Mechanical structure with alignment facility for supporting & aligning the Cryo-Module.

Out of five Sub-assemblies, CDM has started working on drawings of the following three sub-assemblies: (a)Feed box with transfer lines. (b)Feed Cap with transfer lines. (c)End cap with transfer lines.

. Conceptual Arrangement of Feed Box, Feed Cap, End Cap & Transfer Lines. Feed Cap Cryomodule End Cap Feed Box Transfer line Status: Design & Drawing of all three sub- assemblies is taken up.

Acknowledgements ( for providing material and useful discussions) Dr R.K. Bhandari, Director, VECC Dr P.D. Gupta, Director, RRCAT Dr Amit Roy, Director, IUAC Shri C.K. Pithawa, Head, ED, BARC Shri R.L. Suthar, Head, CDM, BARC Smt Manjiri Pande, TPD, BARC Shri Rajesh Kumar, LEHIPA, BARC