Technical overview of ELSA

History And Status

Construction started: June 1983
First beam: February 1988
Total cost of facility: 18.6 MDM
Ann. operating time: up to 5000 h

Accelerator Parameters

  • General
    Accelerated particles: electrons
    Energy: 0.5 - 3.5 GeV
    Ring circumference: 164.4 m
    Tunnel sect. (W x H): 2.5 x 2.3 m
  • Injector system: 2 LINACs
    LINAC 1: 20 MeV
    LINAC 2: 26 MeV, source of polarized electrons (pol. appr. 80 %)
  • Booster Synchrotron
    Type: 50 Hz fast cycling synchrotron
    Output: max. 500 nA at 0.5 - 1.6 GeV
    Injection period: 0.45 usec or 0.8 turns of ELSA
    Inflector type: septum magnet
  • Magnet System
    Focusing type: AG, seperated function
    Focusing order: FODO
    Betatron tune: (for extraction) hor. 4.64, vert. 4.60
    No. of Dipols: 24 Length: 2.84 m
    Bending field: max. 1.07 T
    No. of Quadrupols: 32 (+4 aircore) Length: 0.45 m
    Gradient: max. 7.7 T/m
    No. short straight sect.: 24 Length: 1.50 m
    No. long straight sect.: 8 Length: 4.69 m
    Rise time: 0.2-5 s
    Flat-top-time: 0.5-140 s (relevant for post-accelerator mode of operation only)
    Power input peak: 3.7 MW, mean: 1.6 MW
  • Acceleration RF System (2 systems)
    RF frequency: 499.67 MHz
    Harmonic number: 274
    No. cavities: 2 1
    Length: 1.5 m 0.3 m
    RF power input peak: 250 kW 50 kW
    Radiation loss: 1225 keV/turn at 3.5 GeV
  • Vacuum System
    Material of vac. chamber: stainless steel
    Aperture of vac. chamber: typically 100 x 50 mm
    Average pressure: 5x10-9 mbar (without beam)
  • Extraction System
    Method: hor. betatron resonance Q = 14/3
    resonance strength controlled by sextupoles
    Rate control: spillout controlled by ironless quads
    Length of spill: 20 ms to 60 s

Accelerator Performance

  • Modes of operation
    Mode 1: Stretcher
    Mode 2: Post-accelerator
    Mode 3: Synchrotron Radiation Source
  • Energy
    Mode 1: 0.5 - 1.6 GeV
    Mode 2: 0.5 - 3.5 GeV
    Mode 3: 1.6 - 3.0 GeV
  • Intensity
    • internal beam:
      Mode 1: 2 - 10 mA
      Mode 2: 15 - 80 mA
      Mode 3: 25 - 250 mA
    • external beam:
      Mode 1: 10 pA - 100 nA
      Mode 2: 1 pA - 20 nA
  • Duty Factor
    1. 98% (macroscopic), 60% (with microstructure)
    2. up to 95% (macroscopic), up to 85% (with microstructure) (depending on the final energy and the intensity of the external beam)
  • Lifetime in SR mode: up to 6 h (25 mA at 2.3 GeV)
  • Research Program
    • Electron beams: 2
    • SR beam lines: 7
    • Number of users
      electron beams: 2 (collaborations with external groups)
      SR: 2 groups of our Physics Institute and
      1 external group

Letzte Bearbeitung: 7.06.2002, 10:54 - F. Frommberger