Accelerator Design: the nuts and bolts

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Accelerator Designthe nuts and boltsand
gaskets and resistors

• Elvin Harms
• Beams Division/Fermilab
• Harms_at_fnal.gov cosmo.fnal.gov

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Introduction

• Scratch the surface overview
• What goes into making an accelerator work
• Perspective of big machines
• Principles applicable to all types of
  accelerators
• Interactive

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What makes up a synchrotron?

• Two primary components
• Radiofrequency system
• Impart energy to the particle beam
• Acceleration
• Maintain beams energy (synchrotron light)
• Maintain structure (Colliding beams)
• Magnet system
• Keep the beam focused
• Keep the beam on course

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Magnets

• Electromagnets
• Conventional
• Water or air-cooled
• Copper or aluminum coils
• Iron shapes and contains the field
• Superconducting
• Liquid helium cooled
• Higher fields gt higher energies
• Coil placement critical to field
• Permanent

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Magnets

• Gradient
• Combined function

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Magnets

• Separated function
• Focusing and bending are done by separate magnets

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Magnets

• Flavors
• Dipoles
• Quadrupoles
• Correctors
• trim dipoles
• (skew) quadrupoles
• Sextupoles
• even higher order
• Special purpose
• Injection/Extraction
• Light sources

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Magnets

• Flavors

Sextupole
Quadrupole
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Radiofrequency systems

• Low level
• Frequency
• Amplitude (voltage)
• feedback
• High level
• Accelerating cavities
• Amplification

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Piecing the machine together

• Cascade of accelerators
• Different technologies are more efficient in
  different energy regimes
• Ion sources
• Injectors
• Collectors
• Transfer lines
• End accelerator

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Piecing the machine together
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Piecing the machine together

• Power
• Accelerators require lots of it!
• Stable and reliable source

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Piecing the machine together

• Power
• Magnets connected in series
• Distribution
• Regulation/feedback loops
• Current changes through a component leads to
  changes in beam behavior (never better)

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Piecing the machine together

• Contain the beam in a pipe
• Vacuum
• Particles travel large distances through a
  machine
• Scattering by air can lead to reduced beam
  quality
• emittance growth
• energy loss

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Piecing the machine together

• Vacuum
• Quality 10-7 mbar and lower
• Distributed pumping
• Ion pumps, TSPs, cryo pumping
• Pick the correct materials and seals
• Meticulous cleaning beforehand
• UHV bake the chamber in place

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Piecing the machine together

• Cooling
• Virtually every component requires some sort of
  external cooling
• Water is most common medium
• Superconducting components require cryogens
• Coolant should be in as direct contact with heat
  load as possible (best thermal transfer)

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Piecing the machine together

• Water Cooling
• Conventional magnet coils typically have coolant
  hole through middle of conductor
• Water must be low conductivity (deionized) since
  water current flow together
• Minimze particulates small orifices
• Remove the free oxygen
• Regulate the temperature

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Piecing the machine together

• Cryogenic Cooling
• Superconducting coils bathed in liquid helium at
  4.6K
• Lots of refrigeration (significant power use)
• Low heat loss
• Magnets are super thermos bottles

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Piecing the machine together

• Enclosure
• Electrical and Radiation hazards when operating
• Personnel protection

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Piecing the machine together

• Equipment housing
• Want power supplies and other interface equipment
  as close as possible, but accessible

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Keeping it all together / Making it work

• Controls system
• Monitor and Control
• Timing
• Fast response
• Beam removal
• Coordination
• Human interface

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Keeping it all together / Making it work

• Alignment
• Keep it in line!
• Tevatron 150 to 800 GeV in 30 seconds
• t0 21ms
• C 4 miles
• gt 1.4 million miles traveled during acceleration
  alone

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Keeping it all together / Making it work

• Alignment
• Where is it?
• Position of components with respect to each other
• Macro-positioning

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Keeping it all together / Making it work

• Alignment
• Move it
• Reference system
• Fixturing
• Component stands
• Remote positioning

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Keeping it all together / Making it work

• Diagnostics Ardens talk tomorrow

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Where does the beam go?

• Experiments / End Users
• Internal to machine
• Interaction regions
• Beam quality/size
• External
• Rate, energy, size, and location to deliver beam
• Single-turn
• Resonant extraction

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Resources

• People are the most important component
• Other resources
• Books
• Schools, Workshops, conferences
• Web