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

SCU R&D Review, Jan. 31, 2014 Outline of Presentation Meeting Agenda LCLS-II Performance 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.

SCU R&D Review, Jan. 31, 2014 DRAFT Agenda for Jan. 31 Review * (2014) * Carried out by teleconference to save travel. Chairman assembles committee response in writing within 2 weeks (Feb. 14, 2014) Meeting Site at (no password needed): 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)-

SCU R&D Review, Jan. 31, 2014 LCLS-II Design Summary New 4-GeV CW linac (1 MHz) and 2 new FELs (~2020) 2 New Permanent Magnet (PM) adjustable gap undulators SXR FEL: keV (SASE and self-seeded) HXR FEL: 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) 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 3 rd km of the SLAC tunnel. HXR FEL SXR FEL

SCU R&D Review, Jan. 31, 2014 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 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.

SCU R&D Review, Jan. 31, 2014 SCU’s Provide Real Performance Enhancement SCU (Nb 3 Sn) SCU (NbTi) PM (NdFeB) PM (in-vac) gap = 7.5 mm (5.7 mm for in-vac  same stay-clear) Much higher fields for a given period and gap (planar undulators) LCLS-II PMU u = 26 mm B pk = 1.0 T gap = 7.2 mm

SCU R&D Review, Jan. 31, 2014 Examine Field’s Impact on LCLS-II Undulator Length The next 2 slides assume the following: 4-GeV electron energy (1 kA,  = 0.45  m,  E = 500 keV, etc.) 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 18L G (based on beam brightness), plus 50% longer for self-seeding Compare in-vacuum and out-of-vacuum Permanent Magnets (NdFeB), and SCUs (NbTi & Nb 3 Sn) – 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)…

SCU R&D Review, Jan. 31, 2014 Undulator Length vs. e  Energy for LCLS-II HXR PM In-Vac NbTi Nb 3 Sn u = 27.5 mm, 24.8 mm, 20.3 mm, 18.7 mm (4 GeV) keV Self-Seeded (SS) u = 16.3 mm u = 20.3 mm u = 18.7 mm g = 7.5 mm  = 0.45  m I pk = 1 kA  E = 500 keV  = 15 m g = 7.5 mm  = 0.45  m I pk = 1 kA  E = 500 keV  = 15 m Period varies with energy to maintain lower-limit tuning range (1.2 keV)

SCU R&D Review, Jan. 31, 2014 Und. Length Comparison for LCLS-II HXR Self-Seeded + 20% PM In-Vac NbTi Nb 3 Sn u = 27.5 mm, 24.8 mm, 20.3 mm, 18.7 mm PM sensitive to  x,y 5 keV SS not possible stay-clear = 5.7 mm abc def  -bunching not incl. u defined by this

SCU R&D Review, Jan. 31, 2014 Compare Baseline LCLS-II with LCLS-I (Cu linac) PM, u = 26 mm (project baseline) LCLS-I LCLS-I FEL Performance Compromised with new PMU H.-D. Nuhn

SCU R&D Review, Jan. 31, 2014 Compare Nb 3 Sn ( u = 20 mm) LCLS-II with LCLS-I Nb 3 Sn, u = 20 mm LCLS-I FEL Further Enhanced with 20-mm SCU H.-D. Nuhn

SCU R&D Review, Jan. 31, 2014 SCU R&D Plan in Brief ANL… Builds 2-m test cryostat (based on existing design at APS) Build & test 1.5-m long NbTi prototype planar undulator ( u  21.0 mm) LBNL… Build & test 1.5-m long Nb 3 Sn prototype planar undulator ( u  18.5 mm) Develop and tune each of the NbTi and Nb 3 Sn 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

SCU R&D Review, Jan. 31, 2014 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 Start SCU R&D End R&D Start Und. Installation Production UndulatorProduction SCU R&D Linac and Cryo Install Complete

SCU R&D Review, Jan. 31, 2014 Review Committee and Charge NameInstitute AddressConfirmed Mikael Eriksson, chairMax – 12/18/13 Sara – 12/18/13 David – 12/17/13 Joachim – 12/18/13 Johannes – 01/08/14 Review Committee: Charge to the Committee: 1.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? 2.If the plan appears insufficient, what recommendations can the committee make to improve the chances for supporting a baseline change within 18 months? 3.What further alterations might be made to solidify the plan and move it forward in time or reduce costs?

SCU R&D Review, Jan. 31, 2014 End

SCU R&D Review, Jan. 31, 2014 Compare Nb 3 Sn ( u = 18.5 mm) LCLS-II with LCLS-I Nb 3 Sn, u = 18.5 mm LCLS-I LCLS-I FEL Performance Enhanced with New SCU H.-D. Nuhn

SCU R&D Review, Jan. 31, 2014 Und. Length with 4-mm Stay Clear (5.8 mm gap)PM In-Vac NbTi Nb 3 Sn u = 25.0 mm, 22.0 mm, 18.6 mm, 17.0 mm stay-clear = 4.0 mm

SCU R&D Review, Jan. 31, 2014 Prototype Undulator Parameters