Advanced and Future Advanced and Future Accelerator TechniquesAccelerator Techniques

Is There Life Is There Life inin HEP? HEP?

E. ColbyE. Colby

Stanford Linear Accelerator CenterStanford Linear Accelerator CenterAccelerator Research Department BAccelerator Research Department B

SLUO Annual MeetingSLUO Annual Meeting

July 7, 2000July 7, 2000

Key Accelerator Key Accelerator TechnologiesTechnologies

Electron Colliders: NLC, NElectron Colliders: NLC, N22LC,...LC,...– Polarized particle sourcesPolarized particle sources– Acceleration SystemAcceleration System– Final focus opticsFinal focus optics

Hadron Colliders: LHC, VLHC,...Hadron Colliders: LHC, VLHC,...– Particle sources Particle sources – Bending dipolesBending dipoles– Final focus opticsFinal focus optics

Key Accelerator Key Accelerator TechnologiesTechnologies

Muon Colliders: FMC,…Muon Colliders: FMC,…– Very high intensity synchrotron (5e13 ppp)Very high intensity synchrotron (5e13 ppp)– High power conversion targets (5-7 MW)High power conversion targets (5-7 MW)– Efficient capture optics (20-31 T Solenoid)Efficient capture optics (20-31 T Solenoid)– Rapid emittance damping systems (Rapid emittance damping systems (<1 <1 s)s)– Large aperture acceleratorLarge aperture accelerator– Collider ring design (decay neutrinoCollider ring design (decay neutrino– Final focus opticsFinal focus optics

Other Required Other Required TechnologiesTechnologies

General transport opticsGeneral transport optics Beam diagnosisBeam diagnosis Feedback systemsFeedback systems Control systemsControl systems Active and passive alignment systemsActive and passive alignment systems Vacuum systemsVacuum systems . . .. . .

Key Accelerator Key Accelerator TechnologiesTechnologies

Electron Colliders: NLC, NElectron Colliders: NLC, N22LC,...LC,...– Polarized particle sourcesPolarized particle sources– Acceleration SystemAcceleration System– Final focus opticsFinal focus optics

Hadron Colliders: LHC, VLHC,...Hadron Colliders: LHC, VLHC,...– Particle sources Particle sources – Bending dipolesBending dipoles– Final focus opticsFinal focus optics

AccelerationAcceleration

Couple power efficiently from an Couple power efficiently from an external source to the beamexternal source to the beam– Power SourcePower Source– Power transmission systemPower transmission system– Coupling structureCoupling structure

“Starting from the 1930s, the energy has increased-- by about a factor of 10 every six to eight years… this spectacular achievement has resulted from a succession of technologies rather than from construction of bigger and better machines of a given type.” W. K. H. Panofsky, 1997.

Accelerator Progress of the Last 35 Years

Acceleration MethodsAcceleration Methods

Traditional slow-wave accelerationTraditional slow-wave acceleration– Normal-conducting Normal-conducting – Super-conducting Super-conducting

Plasma-based accelerationPlasma-based acceleration Laser-driven acceleration Laser-driven acceleration Inverse radiative processInverse radiative process Negative resistivity (Čerenkov Negative resistivity (Čerenkov

Amplifier)Amplifier)

Slow-wave StructureSlow-wave StructureBased AccelerationBased Acceleration

F=e EF=e Eoo sin( sin( t-k z+ t-k z+oo), choose ), choose /k=V/k=Vbeam, beam, oo==/2/2

V~ c

Normal Conducting Structure PerformanceNormal Conducting Structure Performance

SLC: 2.856 GHz, SLC: 2.856 GHz, 17 MeV/m, 17 MeV/m, (N~1000, 86 cells)(N~1000, 86 cells)

NLC: 11.424 GHz, NLC: 11.424 GHz, 67 MeV/m (N=1, 67 MeV/m (N=1, (DDS1), 206 cells)(DDS1), 206 cells)

CLIC: 30.0 GHz, CLIC: 30.0 GHz, 125 MeV/m (N=1, 125 MeV/m (N=1, (CTF1), 150 cells) (CTF1), 150 cells)

Future Normal Conducting Future Normal Conducting StructuresStructures

Photonic Band Gap StructuresPhotonic Band Gap Structures DDS 30 GHzDDS 30 GHz 91.392 GHz91.392 GHz

– ““Zipper” StructureZipper” Structure– ““COMPACC” StructureCOMPACC” Structure– Muffin TinMuffin Tin– KlystronsKlystrons

Superconducting Structure Superconducting Structure PerformancePerformanceTESLA: 1.3 GHz Niobium Cavities (9 cells, standing wave)TESLA: 1.3 GHz Niobium Cavities (9 cells, standing wave)

TTF Goal of TTF Goal of 15MeV/m 15MeV/m attainedattained

TESLA-500 Goal TESLA-500 Goal of 25 MeV/m of 25 MeV/m appears appears attainableattainable

Plasma-Based Acceleration Plasma-Based Acceleration SchemesSchemes

Laser Beat-Wave Accelerator (LBWA)Laser Beat-Wave Accelerator (LBWA)

Laser Wakefield Accelerator (LWFA)Laser Wakefield Accelerator (LWFA)

Self-Modulated Laser Wakefield Accelerator (SMLWFA)Self-Modulated Laser Wakefield Accelerator (SMLWFA)

q 2

1

1- 2= q++ ++++

- - - - - -

q

++ ++++

- - - - - -

q

++ ++++

- - - - - -

<q

>>q

Raman Scattering

++ ++++

Accelerated Bunch

Accelerated Bunch

Accelerated Bunch

- - - - - -

- - - - - -

Plasma-Based Acceleration Plasma-Based Acceleration SchemesSchemes

Beam-Driven Wakefield Accelerator (PBWA)Beam-Driven Wakefield Accelerator (PBWA)

Crystal Channeling AcceleratorCrystal Channeling Accelerator

q

++ ++++

- - - - - -

z<c q

++ ++++

Drive Bunch

Accelerated Bunch

Ions form guiding channel; plasma waves induced in atomic electron clouds form accelerating potential

1

Experimental Demonstration ofExperimental Demonstration of Self-Modulated Laser WakefieldSelf-Modulated Laser WakefieldAcceleration (1998)Acceleration (1998)

RAL/UCLA: 160 GeV/m RAL/UCLA: 160 GeV/m

L=4 mm, 20 TW, 10L=4 mm, 20 TW, 101010 e e--

NRL: 500 GeV/m NRL: 500 GeV/m

L=1 mm, 2 TW, 10L=1 mm, 2 TW, 1088 e e--

U of Mich.: 200 GeV/m U of Mich.: 200 GeV/m

L=1 mm, 4 TW, 10L=1 mm, 4 TW, 101010 e e--

Plasma Wakefield Plasma Wakefield Acceleration Acceleration

Advantages:Advantages:– Structure is already broken down!Structure is already broken down!– Very high gradients possible E [GeV/cm] ~ Very high gradients possible E [GeV/cm] ~ n [cmn [cm-3-3]]– Plasma densities of 10Plasma densities of 101818-10-101919 [cm [cm-3-3] have been achieved ] have been achieved

Disadvantages:Disadvantages:– Short wavelength Short wavelength short Rayleigh range short Rayleigh range short short

interaction length (Laser guiding)interaction length (Laser guiding)– Accelerated particle bunch dimensions must be small Accelerated particle bunch dimensions must be small

compared to plasma wavelength to preserve beam compared to plasma wavelength to preserve beam qualityquality

– Shot-to-shot reproducibility of plasma density is criticalShot-to-shot reproducibility of plasma density is critical– Synchronization of successive plasma accelerators is Synchronization of successive plasma accelerators is

difficult (auto synchronization via single drive pulse)difficult (auto synchronization via single drive pulse)

crossedlaser beams

electronbeam

Laser Acceleration SchemesLaser Acceleration Schemes

Crossed Gaussian Laser pulses Crossed Gaussian Laser pulses (Stanford/SLAC/Nat’l Tsinghua Univ.)(Stanford/SLAC/Nat’l Tsinghua Univ.)

1 GW, 850nm Ti:Sapphire pulses

Expected Gradient:

150 MeV/m over 1 mm

Reproduced from T. Plettner, “The LEAP Project”, DOE Review Slides, April 14, 2000.

Capillary GuidesCapillary Guides– PropagatingPropagating

– EvanescentEvanescent

Laser Acceleration SchemesLaser Acceleration Schemes

TM010-like mode driven by radially polarized laser

Capillary mode (effectively a surface wave) driven by radially polarized laser

Inverse Radiative Process Inverse Radiative Process AcceleratorsAccelerators

Inverse Smith-Purcell Radiation Inverse Smith-Purcell Radiation (BNL)(BNL)

Inverse Cerenkov Radiation Inverse Cerenkov Radiation (STELLA, STI Optronics/BNL)(STELLA, STI Optronics/BNL)

Inverse Free-Electron-Laser Inverse Free-Electron-Laser (STI/BNL)(STI/BNL)

Microwave IFEL (Yale) 350KeV/mMicrowave IFEL (Yale) 350KeV/m

Inverse Transition RadiationInverse Transition Radiation

Radially polarized laser pulse

Axially polarized laser pulse

Metal grating

Axicon lens

Different Permittivity Region

Active MediumActive Medium

Trigger bunch

LASER MEDIA: Nd:YAG

LASER MEDIA: Nd:YAG

Accelerated bunch

Cerenkov radiation from trigger bunch stimulates emission from laser media, causing amplification of the Cerenkov wakefield. At an appropriate distance behind the trigger bunch, large acceleration fields are present.

L. Schächter, Technion, Israel

Is there a future for Is there a future for accelerator-based HEP?accelerator-based HEP?

Taken from the European Particle Accelerator Conference Proceedings, Stockholm, Sweden, 1998:

Beam RecombinationBeam Recombination