Technical overview of ELSA

History And Status

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

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