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Superconducting Undulator R&D Proposal for LCLS-II

Superconducting Undulator R&D Proposal for LCLS-II. Paul Emma (SLAC) Superconducting Undulator R&D Review Jan. 31, 2014. please MUTE your microphones or turn down volume. Outline of Presentation. Meeting Agenda LCLS-II Performance Requirements and Issues

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Superconducting Undulator R&D Proposal for LCLS-II

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  1. Superconducting Undulator R&D Proposal for LCLS-II Paul Emma (SLAC) Superconducting Undulator R&D Review Jan. 31, 2014 please MUTE your microphones or turn down volume

  2. Outline of Presentation • Meeting Agenda • LCLS-IIPerformance Requirements and Issues • Superconducting Undulators (SCU’s) compared with permanent magnet undulators • SCU impact on LCLS-II Hard X-Ray (HXR) FEL performance • SCU impact on LCLS-I performance (using Cu linac) • Brief SCU R&D Plan (more from other speakers) • Review Charge and Committee This is a review of the R&D Proposal which leads up to a possible design baseline change in 2015, and not an evaluation of that decision.

  3. DRAFT Agenda for Jan. 31 Review* (2014) Meeting Site at (no password needed): https://portal.slac.stanford.edu/sites/ad_public/reviews/scu_rd_jan_2014/ Review Agenda (all times Pacific/SLAC): • 07:00 AM (5 min) Welcome and ChargeNorbert Holtkamp (SLAC) • 07:05 AM (30 min) SCU Advantages in LCLS-IIPaul Emma (SLAC) • 07:35 AM (20 min) Undulator Tolerance EstimatesHeinz-Dieter Nuhn (SLAC) • 07:55 AM (50 min) SCU Development at ANLEfim Gluskin (ANL) • 08:45 AM (10 min) (break) - • 08:55 AM (50 min) SCU Development at LBNLSoren Prestemon (LBNL) • 09:45 AM (20 min) SCU Field MeasurementsDiego Arbelaez (LBNL) • 10:05 AM (25 min) (executive session)Committee Only • 10:30 AM (adjourn) - Chairman assembles committee response in writing within 2 weeks (Feb. 14, 2014) * Carried out by teleconference to save travel.

  4. LCLS-II Design Summary • New 4-GeV CW linac (1 MHz) and 2 new FELs (~2020) • 2 New Permanent Magnet (PM) adjustable gap undulators • SXRFEL: 0.2 - 1.3 keV (SASE and self-seeded) • HXRFEL: 1.2 - 5.0 keV (SASE and self-seeded?) • PM for HXR undulator barely allows 5.0 keV in SASE (no self-seeding unless 4 keV or less) – existing und. hall is 150 m • Will also replace existing LCLS-I und. with adj.-gap PMU (HXR) • Radiation damage to PM’s is a major issue at 1 MHz (gap?) • HXR FEL based on 150-m long PM-undulator at 4 GeV is very sensitive to e- emittance when tuned above 3.5 keV (risk) SXR FEL HXR FEL Schematic of the LCLS-II facility with the new SCRF linac and two new undulators, along with the existing copper (Cu) linac, undulator and experimental halls. The “Cu Linac” is in the 3rd km of the SLAC tunnel.

  5. Superconducting Undulator Motivation Using an SCU for the LCLS-II HXR undulator… • …allows full LCLS-II performance to 5 keV (SASE & self-seeded) and with 50-70 m less undulator (or more taper) • …has orders of mag. less sensitivity to rad. dose • …is much less sensitive to e-emittance (new high-rate gun) • …produces very low pressure in a small vacuum chamber (gas scattering at 1 MHz) • …enhances LCLS-I FEL power, whereas a new PM degrades it.

  6. SCU’s Provide Real Performance Enhancement Much higher fields for a given period and gap (planar undulators) SCU (Nb3Sn) SCU (NbTi) PM (in-vac) LCLS-II PMU lu = 26 mm Bpk = 1.0 T gap = 7.2 mm PM (NdFeB) gap = 7.5 mm (5.7 mm for in-vac same stay-clear)

  7. Examine Field’s Impact on LCLS-II Undulator Length The next 2 slides assume the following: • 4-GeV electron energy (1 kA, ge = 0.45 mm, sE = 500 keV, etc.) • 1.2 - 4.0 keV photon tuning range (SASE & self-seeded) • Full-height magnetic gap of 7.5 mm (chamber gap is 5.7 mm) • Und. period set by lower-limit photon energy (1.2 keV) for FEL resonance at highest field possible for this gap and technology • Und. length set by max. photon energy (4 keV), assuming 18LG (based on beam brightness), plus 50% longer for self-seeding • Compare in-vacuum and out-of-vacuum Permanent Magnets (NdFeB), and SCUs (NbTi & Nb3Sn) – all with same chamber gap • Und. length includes 1.15-m breaks, 3.4-m segments, +20% for margin, and 4-m extra space for self-seeding monochromator • Examine total length sensitivity to main parameters (see next)…

  8. Undulator Length vs. e- Energy for LCLS-II HXR 1.2 - 4.0 keV Self-Seeded (SS) PM In-Vac NbTi Nb3Sn Period varies with energy to maintain lower-limit tuning range (1.2 keV) lu = 16.3mm lu = 18.7mm lu =20.3mm g = 7.5 mm ge = 0.45 mm Ipk = 1 kA sE = 500 keV b = 15 m lu = 27.5 mm, 24.8 mm, 20.3 mm, 18.7 mm (4 GeV)

  9. Und. Length Comparison for LCLS-II HXR a b c PM In-Vac NbTi Nb3Sn Self-Seeded + 20% stay-clear = 5.7 mm PM sensitive to gex,y d e f lu defined by this m-bunching not incl. 5 keV SSnot possible lu = 27.5 mm, 24.8 mm, 20.3 mm, 18.7 mm

  10. Compare Baseline LCLS-II with LCLS-I (Cu linac) LCLS-I FEL Performance Compromised with new PMU PM, lu= 26 mm (project baseline) LCLS-I H.-D. Nuhn

  11. Compare Nb3Sn (lu = 20 mm) LCLS-II with LCLS-I LCLS-I FEL Further Enhanced with 20-mm SCU Nb3Sn, lu= 20 mm H.-D. Nuhn

  12. SCU R&D Plan in Brief • ANL… • Builds 2-m test cryostat (based on existing design at APS) • Build & test 1.5-m long NbTiprototype planar undulator (lu 21.0 mm) • LBNL… • Build & test 1.5-m long Nb3Sn prototype planar undulator (lu 18.5 mm) • Develop and tune each of the NbTi and Nb3Sn undulators • Both Labs… • Develop field measurement and field correction techniques • Demonstrate predicted field, field quality, end-field corrections, field measurement and tuning, cold mass fiducialization, and integration of cold mass into cryostat • Goal: Within 18 months deliver 2 fully functional, 1.5-m long, SC prototype undulators which meet LCLS-II specifications

  13. SCU R&D and LCLS-II Construction Time-Line • 17-Month SCU R&D (to ~May 2015) • 3-Year production cycle for 33 SCU segments (~3 m/ea) • Installation of LCLS-II undulator starts mid-2018 Undulator Production SCU R&D 2014 2015 2016 2017 2018 2019 2020 Start SCU R&D End R&D Start Und. Installation Start Und. Production Linac and Cryo Install Complete

  14. Review Committeeand Charge Review Committee: Charge to theCommittee: • Is the SCU R&D plan technically sound, and is it well enough defined in scope, schedule, and cost so as to produce definitive results that can support a baseline design change to the hard x-ray LCLS-II undulator, by May 2015? • If the plan appears insufficient, what recommendations can the committee make to improve the chances for supporting a baseline change within 18 months? • What further alterations might be made to solidify the plan and move it forward in time or reduce costs?

  15. End

  16. Compare Nb3Sn (lu = 18.5 mm) LCLS-II with LCLS-I LCLS-I FEL Performance Enhanced with New SCU Nb3Sn, lu= 18.5 mm LCLS-I H.-D. Nuhn

  17. Und. Length with 4-mm Stay Clear (5.8 mm gap) PM In-Vac NbTi Nb3Sn stay-clear = 4.0 mm lu = 25.0 mm, 22.0 mm, 18.6 mm, 17.0 mm

  18. Prototype Undulator Parameters

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