Integrable Optics Test Accelerator Sergei Nagaitsev Fermilab April 3, 2013

Background and History In 2006, Fermilab was asked to lead the US ILC/SRF R&D Program  we felt that the most effective way to do that was to learn by doing Construction of Test Facility began in 2006 as part of ILC/SRF R&D and later American Recovery and Reinvestment Act (ARRA) 2 S. Nagaitsev, PASI 2nd annual meeting, Apr. 3-5, 2013 It was recognized early in the planning process that an electron beam meeting the ILC performance parameters was itself a power resource of interest to the wider Advanced Accelerator R&D (AARD) community The Facility was motivated by the goal of building, testing and operating a complete ILC RF unit to:  Develop and demonstrate industrial and laboratory capability for producing state-of- the-art SCL components, assemble into a fully functioning system (photo-injector, bunch compressor, three 1.3 GHz ILC CMs, beamlines to dumps)  To carry out full beam-based system tests with high-gradient cryomodules and demonstrate ILC beam quality

Background and History In planning the construction we therefore wanted to ensure that the facility offered something of enduring value when it was completed.  Hence, the investment in establishing a flexible facility that would readily support an AARD user program. For those reasons the ARRA-funded facility construction incorporated space for  additional ILC cryomodules to increase the beam energy to 1.5 GeV,  space for multiple high-energy beamlines,  space for a small circular ring for the exploration of advanced concepts,  capability of transporting laser light into and out of the accelerator enclosure,  an adequately-sized control room To date, an investment of $74M has been made, including $18M of ARRA funding, representing ~80% completion of the facility In June 2012, anticipating the completion of the ILC R&D Program, Fermilab was directed to prepare a proposal for the AARD program.  Proposal submitted to the DOE in Feb S. Nagaitsev, PASI 2nd annual meeting, Apr. 3-5, 2013

Our Proposal 4 S. Nagaitsev, PASI 2nd annual meeting, Apr. 3-5,

We proposed to establish a proposal-driven Accelerator R&D User Facility at Fermilab’s Advanced Superconducting Test Accelerator (ASTA) To do that requires: 1. Supporting the completion of ASTA in a phased approach:  Build out the linear accelerator to ~800 MeV with three Cryomodules associated beam transport lines, dumps and support systems  Construct the Integrable Optics Test Accelerator (IOTA) A small, flexible storage ring to investigate beam dynamics of importance to intensity frontier rings  In further phases Add proton capability to IOTA (by reusing existing HINS equipment) Increase peak current of compressed electron bunches by installation of 3.9 GHz system 2. Supporting the Operation of an Accelerator R&D User Program  Support staff required to operate a 9 month/year proposal-driven Accelerator R&D program 5 S. Nagaitsev, PASI 2nd annual meeting, Apr. 3-5, 2013

Substantial Investments Have Already Been Made At ASTA 6 Tunnel extension: $4.5M Beam Dumps: $2M Magnets and Power Supplies: $4M S. Nagaitsev, PASI 2nd annual meeting, Apr. 3-5, 2013 RF Power Systems: $8M Cryomodules: $15M

7 S. Nagaitsev, PASI 2nd annual meeting, Apr. 3-5, 2013 New Muon Lab CMTF New Muon Lab – home of ASTA, CMTF – home of PXIE

S. Nagaitsev, PASI 2nd annual meeting, Apr. 3-5, Facilities

ASTA : Schematically (at the end of Stage IV) S. Nagaitsev, PASI 2nd annual meeting, Apr. 3-5,

ASTA : Upstream part Shows 3 SCRF CMs (1 st CM – at Stage I.2, 2 more – Stage II) S. Nagaitsev, PASI 2nd annual meeting, Apr. 3-5, ‘ (74 m) 42‘ (13 m)

ASTA : Downstream part proton RFQ not pictured (Stage III) S. Nagaitsev, PASI 2nd annual meeting, Apr. 3-5, ‘ (70 m) 76‘ (23 m)

Experimental Areas 1 & 2 Parameter ValueRangeUnit Comments Energy Exp A MeV maximum determined by booster cavity gradients Energy Exp A MeV 1500 MeV with 6 cryomodules Bunch charge nC maximum determined by cathode QE and laser power Bunch spacing33310-∞ ns laser power Bunch train T11 bunch ms maximum limited by modulator and klystron power Train rep rate Hz minimum may be determined by egun T-regulation and stability considerations Emittance rms norm5 100 π  m maximum limited by aperture and beam losses Bunch length rms ps min obtained with Ti:Sa laser; maximum obtained with laser pulse stacking Peak current3>9 kA 3 kA with low energy bunch compressor; 9 kA possible with 3.9 GHz linearizing cavity S. Nagaitsev, PASI 2nd annual meeting, Apr. 3-5, * 3.2nC × 3000 bunches × 5 Hz × 0.82 GeV = 40 kW

Experimental Area 3: IOTA ParameterValueUnit Circumference38.7m Bending dipole field0.7T RF voltage50kV Electron beam energy150MeV Number of electrons Transv. emittance r.m.s. norm2 π  m Proton beam energy2.5MeV Proton beam momentum70MeV/c Number of protons Transv. emittance r.m.s. norm π  m S. Nagaitsev, PASI 2nd annual meeting, Apr. 3-5,

ASTA Science Thrusts Intensity Frontier of Particle Physics Nonlinear, integrable optics Space-charge compensation 14 Energy Frontier of Particle Physics Optical Stochastic Cooling Advanced phase-space manipulation Flat beam-driven DWFA in slabs Superconducting Accelerators for Science Beam-based system tests with high-gradient cryomodules Long-range wakes Ultra-stable operation of SCLs Novel Radiation Sources High-brightness x-ray channeling Inverse Compton Gamma Ray source Stewardship and Applications Generation and Manipulation Ultra-Low Emittance Beams for Future Hard X-ray FELs XUV FEL Oscillator S. Nagaitsev, PASI 2nd annual meeting, Apr. 3-5, 2013

Intensity Frontier Proposal: Experimental demonstration of integrable optics lattice at IOTA  FNAL, SNS, JINR, Budker INP, BNL, JAI, U. of Colorado, U. of Chicago Proposal: Space Charge Compensation in High Intensity Circular Accelerators  FNAL, support from CERN, BNL Experiments require the IOTA Ring  Difficult to implement needed linear optics in existing facilities  Lack of ring facilities in the US S. Nagaitsev, PASI 2nd annual meeting, Apr. 3-5,

A roadmap for high-intensity rings 1. Increase dynamic aperture of rings with strong sextupoles and octupoles  Single particle dynamics  Also, addressed by the light-source community 2. Develop the theoretical basis of beam instabilities with strong space charge 3. Develop highly-nonlinear focusing lattices with reduced chaos 4. Reduce chaos in beam-beam effects 5. Ultimately, develop accelerators for super-high beam intensity  Self-consistent or compensated space-charge  Strong non-linearity (for Landau damping) to suppress instabilities  Stable particle motion at large amplitudes S. Nagaitsev, PASI 2nd annual meeting, Apr. 3-5, Addressed by ASTA Being addressed now

S. Nagaitsev, PASI 2nd annual meeting, Apr. 3-5, Integrable Optics at IOTA Main goals for studies with a pencil electron beam:  Demonstrate a large tune spread of ~1 (with 4 lenses) without degradation of dynamic aperture ( minimum 0.25 )  Quantify effects of a non-ideal lens and develop a practical lens (m- or e-lens)

S. Nagaitsev, PASI 2nd annual meeting, Apr. 3-5, ASTA : Downstream part (now) beam dump IOTA

S. Nagaitsev, PASI 2nd annual meeting, Apr. 3-5, Integrable Optics: Integrable Optics: Motivation The main feature of all present accelerators – linear focusing lattice: particles have nearly identical betatron frequencies (tunes) by design.  Hamiltonian has explicit time dependence  All nonlinearities (both magnet imperfections and specially introduced) are perturbations and make single particle motion unstable (non-integrable) due to resonant conditions Stability depends on initial conditions Regular trajectories for small amplitudes Resonant islands (for larger amplitudes) Chaos and loss of stability (for large amplitudes)

S. Nagaitsev, PASI 2nd annual meeting, Apr. 3-5, Does Focusing Need to be Linear? Are there “magic” nonlinearities with zero resonance strength? The answer is – yes (we call them “integrable”) Search for a lattice design that is strongly nonlinear yet stable  Orlov (1963) -- attempt failed (non-integrable)  McMillan (1967) – first successfull 1-D example  Perevedentsev, Danilov ( ) – several 1D, 2D examples  Cary and colleagues (1994) – approximate integrability Our goal (with IOTA) is to create practical nonlinear accelerator focusing systems with a large frequency spread and stable particle motion.  Danilov, Nagaitsev, Phys. Rev. ST Accel. Beams 13, (2010)

S. Nagaitsev, PASI 2nd annual meeting, Apr. 3-5, Nonlinear Lenses “Integrable Optics” solutions:  Make motion regular, limited and long- term stable (usually involves additional “integrals of motion”) Can be Laplacian (with special magnets, no extra charge density involved) Or non-Laplacian (with externally created charge –e.g. special e-lens or beam-beam E(r) ~r/(1+r^2) Both types will be tested in IOTA

S. Nagaitsev, PASI 2nd annual meeting, Apr. 3-5, Concept: 2-m long nonlinear magnet

S. Nagaitsev, PASI 2nd annual meeting, Apr. 3-5, A single nonlinear lens A single 2-m long nonlinear lens creates a tune spread of ~0.25. FMA, fractional tunes Small amplitudes (0.91, 0.59) Large amplitudes νxνx νyνy

S. Nagaitsev, PASI 2nd annual meeting, Apr. 3-5, System: linear FOFO; 100 A; linear KV w/ mismatch Result: quickly drives test-particles into the halo 500 passes; beam core (red contours) is mismatched; halo (blue dots) has 100x lower density Space Charge Effects in Linear Optics Lattice Tech-X simulations dQ_sc ~ 0.7

S. Nagaitsev, PASI 2nd annual meeting, Apr. 3-5, System: octupoles; 100 A; generalized KV w/ mismatch Result: nonlinear decoherence suppresses halo 500 passes; beam core (red contours) is mismatched; halo (blue dots) has 100x lower density Space Charge Integrable Optics Lattice with Space Charge dQ_sc ~ 0.7 Tech-X simulations

S. Nagaitsev, PASI 2nd annual meeting, Apr. 3-5, Space Charge Compensation Bringing Protons to IOTA Allows tests of Integrable Optics with protons and realistic Space-Charge beam dynamics studies Allows Space-charge compensation experiments 2.5 MeV RFQ HINS

S. Nagaitsev, PASI 2nd annual meeting, Apr. 3-5, Space Charge Forces & Compensation B=  E Z, beam direction r, across the beam

S. Nagaitsev, PASI 2nd annual meeting, Apr. 3-5, Space-Charge Compensation in Circular Accelerators Goal: Experimental demonstration of the space-charge compensation technique with electron columns/electron lenses at dQ_sc >1 Why ASTA: Need 2.5 MeV high-current protons and IOTA – flexible lattice storage ring Relevant accelerators: All current and future high intensity proton rings (Booster, MI, all LHC injectors, MC rings, etc)

Summary ASTA offers:  A broad range in beam energies ( MeV)  High-repetition rate and the highest power beams available  High beam quality and beam stability  The brightest beams available  Advanced phase-space manipulations (FB, EEX)  Linacs and ring (IOTA), electrons and protons, lasers IOTA scientific goals are well aligned with Fermilab goals and investments in Intensity and Energy Frontiers ASTA is a great opportunity for collaboration, for post- docs and graduate students S. Nagaitsev, PASI 2nd annual meeting, Apr. 3-5,