# Presentation: 398002

## Hasan Padamsee
Cornell University

*Cornell University*

- Technical Goals of the Collaboration,U.S. SRF Infrastructure & Deliverables

## Outline 

- Introductory remarks on SMTF collaboration resources
- Common goals for all projects
- Project specific technical goals
- ILC, PD, RIA, CW...
- Infrastructure in US labs available for SMTF activities
- ILC Deliverables
- Conclusions

## Introduction

- The SMTF collaboration has excellent resources in SRF expertise and existing facilities (shown later)
-  We intend to be a strong collaboration by heavily utilizing available infrastructure and SRF people expertise in all labs.
- No single lab can handle the ILC or PD task
- To meet ILC, PD... goals we will need to upgrade facilities to fill in gaps (more later)
- We have formed the SMTF Technical Collaboration Board (of which I am the chair).
- Members are experts in the technical areas:
- Cavities, Cryomodules, RF, Beam Tests, Industrialization
- We will meet regularly to discuss technical issues, organize workshops, advise SMTF board.

## Common Goal for All Projects Establish Overall Infrastructure 

- Establish SMTF Infrastructure in Meson Hall & New Meson for ILC, PD, CW, and RIA Activities
- Cryomodule test areas
- Beam test areas
- Cavity test areas (in later phases)
- Cryogenics...(*Talk by Arkady*)
- Phase I & II : 60 W at 2 K initial (refrigerator exists), & cryo at 4K
- Phase III: 300 W  at 2 K later, 300 W at 4 K, 5 kW at 40 K
- RF...(*Talks by Chase & Wildman*)
- Phase 1- one 15 MW modulator (B1), one 5 MW klystron
- Phase 2- one 15 MW modulator (B1), one 10 MW klystron
- Phase 3- two 15 MW modulators (one new B3), two 10 MW klystrons (one new)
- Shielding....

*See also talk by Limon*

## Slide 5

## ILC - Technical Goals

- Four main arenas
- 1- Cavities and performance
- 2- Cryomodules
- 3- Beam tests
- 4 - US industrial base and industrialization

## (1) Acquire Cavities and Performance

- Enhance infrastructure for cavity treatment and testing at collaborating institutions, & Fermilab (see later slides for existing infra-structure).
- e.g. Jlab  EP 9-cell cavities, vertical test 9-cell cavities
- e.g. Finish cavity treatment facility at Argonne/Fermilab
- e.g. Enhance Cornell BCP and vertical test areas
- Establish process for repeatable high performance           (35 MV/m, Q > 1010) with 9-cell cavities in support of *Baseline Configuration* to be defined at Snowmass
- Get started early with 2-3 DESY cavities
- Acquire Cavities from start-up US industry and from KEK
- Fabricate 1.3 GHz high gradient cavities, in collaboration with laboratories, universities and US industrial partners.

*See also talk by Carter*

##  (2) Acquire Cryomodules

- Acquire cryomodule components from industry
- Test cavities in horizontal test dewar (HTD) at Fermilab
- Assemble cavity-strings
- Assemble cryomodules
- Acquire DESY cryomodule or components
- Assemble as needed
- Develop 4th generation cryomodule

## There is considerable discussion world-wide of many needed improvements.
More compact spacing of cavities
HOM absorber at module interconnect and minimum interconnect spacing
Quadrupole magnet and package 
Mount at center post for best stability, alignment and vibration
Evaluate quad, steerer requirements: field quality, reproducibility, resetability, saturation, hysteresis, persistent currents 
BPM 
Evaluate and develop for better resolution and Clean Room compatibility
Tuner stepping motor placement for reliability 
No. of cavities per module (8 vs 12 vs super-structure)
Better Flange connections- with less nuts & bolts
Input coupler processing improvements
Engineering for industrialization

- More compact spacing of cavities
- HOM absorber at module interconnect and minimum interconnect spacing
- Quadrupole magnet and package
- Mount at center post for best stability, alignment and vibration
- Evaluate quad, steerer requirements: field quality, reproducibility, resetability, saturation, hysteresis, persistent currents
- BPM
- Evaluate and develop for better resolution and Clean Room compatibility
- Tuner stepping motor placement for reliability
- No. of cavities per module (8 vs 12 vs super-structure)
- Better Flange connections- with less nuts & bolts
- Input coupler processing improvements
- Engineering for industrialization

- 4th-Generation Cryomodule

## (4) Beam Tests

- Move injector to New Muon Hall
- Upgrade Injector energy from 15 to 40 MeV *(see Parameters Table next slide)*
- Add 3.9 GHz accelerating and deflecting cavities for bunch compression and diagnostics
- Test modules with beam
- Demonstrate 1.3 GHz cavity operation at 35 MV/m with beam currents up to 10 mA at 0.5 % duty factor.
- Measure key performance aspects
- Long term operation, trip rates, recovery times, dark current, amplitude & phase control, alignment, vibration, input coupler performance, HOM damping...
- Many items to cover long lists in R1, R2, R3 and R4 (detailed TRC - Greg Loew Report) will need significant testing capability beyond time available in TTF-II

## See also talk by Piot

*See also talk by Piot*

## Technology Studies Details(Included here for reference only)

- •	Determine the maximum operating gradient of each cavity & its limitations.
- Evaluate gradient spread and its operational implications.
- Measure dark currents, cryogenic load, dark current propagation, and radiation levels.
- Measure alignment of the quadrupole, cavities and BPM in-situ using conventional techniques (e.g. wire or optical).
- Measure vibration spectra of the cryomodule components, especially the quadrupole magnet.
- Measure system trip rates and recovery times to assess availability.
- •	Develop LLRF exception handling software to automate system and reduce downtime.
- Evaluate failures with long recovery times: vacuum, tuners, piezocontrollers, and couplers.

*See talk by Mishra*

## Physics Measurements Details (Included here for reference only)

- Beam energy:a spectrometer would provide an independent and accurate measurement of the accelerating gradient (rf based techniques are not as accurate).
- Long-range wake-field characterization:Measure frequency spectra of bunch positions downstream of cryomodule to search for high Q cavity dipole modes that could cause beam break-up in the ILC. Correlate these data with HOM power measurements.
- Tests of low-level rf system:demonstrate that a < 0.1% bunch-to-bunch energy spread can be achieved in a 1 msecbunch train.
- Impact of the SCRF cavity on transverse beam dynamics: measure the beam kicks caused by the fundamental mode fields.
- Study beam centering based on HOM dipole signals.

*See talk by Mishra*

##  (5) Start Up US Industrial Base & Activities Toward Industrialization

- Develop and support start-up industrial production capability in US
- AES on board
- Transfer cavity and cryomodule technology to industry
- e.g. Meyer Tool, ADC...
- Pursue paths to large scale industrialization
- Work with industry to reduce costs

*See talk by Funk *

## ILC - Deliverables

- Repeatable process for 35 MV/m, high Q, 9-cell cavities (2008)
- US- ILC 8-cavity cryomodule (2007)
- 4th generation cryomodule design (2008)
- Linac system tests to qualify basic linac building blocks: cavity, couplers, tuners, quads, BPM, module, RF, modulators...
- to meet linac related R1... R4  goals in TRC
- RF controls, low level RF system and instrumentation for ILC
- 3.9 GHz accelerating and deflecting cavities for injector
- Deflecting cavity development also useful for beam diagnostics and to support ILC crab crossing development
- High gradient cavity R&D for Alternate Configuration
- Re-entrant cavity
- Low-loss cavity
- Single Crystal cavity
- Develop US industry
- Transfer cavity and cryomodule technology to industry
- Guide and support  large scale industrialization

## The SC Proton Driver Option

- The Proton Driver is an 8 GeV SRF proton linac
- For Neutrino Super-Beams & other new capabilities at FNAL
- The technology and R&D for the last 85% of the PD linac (1 GeV to 8 GeV) is *identical to the ILC.*
- Beta<1 “Squeezed TESLA” Linac
- “SNS” SCRF linac at   f = 1300 MHz
- “Pulsed RIA” Front End Linac
- spoke SCRF cavities at 325 MHz

*See talk by Foster *

## Proton Driver Goals

- Fabricate test structures and associated cryomodules
- 325 MHz cavities in various ranges (like RIA but improved structures)
- = 0.47 and 0.61, 1300 MHz elliptical cavities
- Demonstrate high gradient operation in pulsed mode of 325 MHz,   < 1 cavities and cryomodules.
- Demonstrate 1.3 GHz,  ~ 0.5-0.8, elliptical cavity operation at > 15 MV/m at Q > 5x109 and a 1% duty factor with multiple cavities being driven by one klystron using fast ferrite phase shifters.
- Demonstrate operation of 1.3 GHz  ILC cavities and module at 27 MV/m with beam currents up to 8 mA with multiple cavities driven by one klystron using fast ferrite phase shifters.
- Demonstrate individual cavity resonance control with multiple cavities driven from one klystron, using fast ferrite phase shifters, at both 1.3 GHz and 325MHz
- Prototype new generation modulators
- 3 ms pulse width beam pulse, rf pulse 4.5 ms

## RIA

- The U.S. Rare Isotope Accelerator Project will include the construction of nearly 500 superconducting cavities of 10 different types to accelerate ions over a velocity range 0.02 < < 0.85.
- Cavity types, cryomodules, couplers, and tuners are similar in design to PD

**LANL  (APT)**

**ANL  (RIA)**

## RIA Goals (Overlap PD)

- Spokes are well developed technology but not tested with high power and not tested with beam
- Expand on-going RIA work, improve design
- Bare cavity tests, string assembly, module assembly
- Test modules
- Higher power couplers than before
- First beam tests with significant beams via PD front end

## CW for Future Light Sources (1)

- Establish cryomodule and beam test areas using =1 pulsed test beam.
- Design and fabricate high Q accelerating cavities and a two cavity-cryomodule
- Demonstrate 20 MV/m CW cavity operation with Q values of ~ 3x1010.
- Jlab 7-cell (Renassence) 1.5 GHz cavities already reach 20 MV/m in vertical cavity tests at Q ≈ 1010.
- Cryomodule tests on the way.

## Higher Q is essential for Future Light Sources Based on CW SRF.

- For future FELs and ERLs, e.g. Cornell, LBNL, MIT, based on linac energies of 0.75 GeV - 5 GeV, the refrigerator will be a major cost driver.
- At 20 MV/m and Q = 1010 => 2 K dynamic heat load is 40 watt/m
- Compare to ILC 2 K heat dynamic heat load of ≈ 1 watt/m
- 5 GeV ERL would need 12 kW of 2 K refrigeration and 18 KW with standard engineering margin.
- Compare : JLAB now has 5 kW at 2 K

## CW for Future Light Sources (2)

- Demonstrate wakefield suppression, HOM absorbers for CW cavities
- Solve heat load management for high CW heat load
- Demonstrate high stability and control of accelerating fields
- Goals: phase error < 0.01° and amplitude error <10-4
- Fabricate deflecting cavities and a two-cavity cryomodule
- Also supports ILC crab cavity development elsewhere.
- Demonstrate  deflecting cavities at transverse kick voltage of 5 MV/m, and Qo > 5x109
- HOM (higher-order modes) and LOM (lower-order modes) damping validation, polarization control

## Role of Deflecting Cavities for an Ultrafast Light Source

- In a downstream radiating magnet or insertion device, the time-correlated transverse kick results in an angular or spatial distribution of the radiation emitted by electrons along the length of the bunch.
- The resulting extended x-ray pulse with correlated distribution may be imaged by asymmetrically-cut crystals or aberration-corrected x-ray optics, to result in an x-ray pulse of approximately picosecond duration.
- After the bunch radiates, the kick introduced is cancelled by a downstream deflecting cavity.
- High repetition rates, in principle as high as 500 MHz (ALS bunch rate), may be achievable using this technique, providing an ultrafast x-ray source with characteristics suitable for a variety of time-resolved photoemission and magnetism experiments.

## Accelerator Physics R&D

- Construct and operate the improved photo-injector for ILC needs and general accelerator R&D
- See earlier Parameter Table of existing injector /compared to Table for upgraded injector/ILC parameters needed
- Provide Beam to test modules
- e.g. Long range and short range wakes, HOM load performance...
- R&D on beam instrumentation, beam diagnostics, rf controls with beams
- Train accelerator scientists.

*See talk by Piot *

## Supporting Basic SRF R&D

- High gradient and high Q R&D
- Understand and improve processing steps in support of 35 MV/m
- Push gradients toward 40+ MV/m in support of R&D for Alternate Configuration (to be defined at Snowmass)
- Fabricate and test 9-cell with new cavity geometry
- Re-entrant geometry, single cell reached 46 - 47MV/m (at Cornell)
- Low-Loss geometry (with KEK & Jlab)
- Single crystal cavities (with Jlab)
- Material research to improve cavity performance in collaboration with partners
- Applied Superconductivity Center, Wisconsin, Northwestern University
- Important R&D not pursued elsewhere
- Dynamics of magnetic flux penetration into superconductors
- Atom by atom analysis of niobium surface from oxide to metal

*See talk by Bauer *

## Review of Existing Facilities

- In upcoming slides, I will show substantial facilities exist in the US for
- Cavity fabrication, preparation and testing
- Cavity string and cryomodule assembly and testing
- We plan to pull in as many of the existing facilities as possible as we gear up SMTF activities
- Some gaps in existing facilities that need to be addressed are
- 9-cell cavity handling
- cleanliness upgrade to reach 35 MV/m reproducibly
-  infrastructure and tooling to meet strict alignment tolerance for cavity strings and cryomodules

## Goals for US Facilities

- Based on experience at DESY & Jlab, there is a need for *Next Generation Facility* and infrastructure to improve flow of operations and maintain high level of performance (covered in upcoming talks on MP9 cryomodule assembly)
- We will need all these facilities to:
- Reach ILC cavity high performance 35 MV/m & reproducibly
-  Assemble ILC cavity strings with stringent cleanliness
- Assemble cryomodules with requisite alignment tolerances
- Support development of US industrial base for ILC & PD
- Support evolving Large Scale Industrialization

## Argonne

## Phase I: The Joint ANL/FNAL Chemistry Facility

**Chemical Processing Rooms**

**Air Scrubber**

**Two sealed chemistry areas, 16 ft ceiling**
**Large air scrubber suitable for RIA cavity production**

## FNAL Chemistry Area for Beta=1

**Remotely controlled, semi-automatic operation**
**Suitable to handle 9-cell 1.3 GHz cavities**
**250 liter acid handling capability**
**<1 minute cavity fill/empty time**

## Techniques: Clean Processing for Low beta Cavities

- Clean techniques from DESY and Jefferson Lab
- are similar for low- and mid-beta cavities
- Ultrapure high-pressure water rinse in clean area
- Clean room assembly of cavity, couplers
- Electropolishing

**High-pressure rinsing**

**Clean room cavity assembly**

**Co-axial half-wave**

**Double spoke**

**Quarter-wave**

## Cornell

## SRF Infrastructure

**SRF Infrastructure**

- Deep Drawing

- Ebeam Welding

- Chemical Etching

- High Pressure Rinsing

- 1000 Sq Ft Clean Room

## Cornell Cavity Test Pits (3)

## Test Stand under prep for 9-cells

- He Saver

- Large Dewar

## Electropolish in Vertical Orientation

- Single Cell method developed
- Needs extension to multicells

## Fermilab

## Slide 39

## Slide 40

## Jlab

## Slide 42

## Slide 43

## JLAB

- Cavity Vertical Test Areas (6)

## Slide 45

## Slide 46

## LANL

## Slide 48

## Slide 49

## Slide 50

## Slide 51

## MSU

## Slide 53

## Conclusions

- SMTF will heavily utilize and expand upon existing SRF expertise and infrastructure at: Argonne, Cornell, Fermilab Jefferson Lab, MSU, LANL
- No single lab can handle the ILC or PD tasks
- SMTF will provide:
- a facility where different module types & linac systems can be assembled, tested &  beam tested
- a collaboration on cold linac technology, cavity fabrication and testing, module development, fabrication and assembly
- facilities enhancement at partner labs to meet goals
- SMTF will allow US to:
- Minimize cost
-  Build cooperation with industry
- Overlap of national experts at one facility will allow exchange of ideas and unify US approach for more effective use of resources
- Build collaboration to prepare/plan to host ILC in US (under direction of ILC- GDE)