Frontend vacuum system

1
Front-end vacuum system
F.Mazzolini
2

• A Front-End is the interface between the Storage
  Ring and one or more Beamlines. It includes all
  the components installed between a Light Port in
  the Storage Ring and the first optical element of
  the connected Beamline. It should
• protect the personnel from accidental exposure
  to high-energy ionising beams or to the intense
  beam of synchrotron light
• protect the vacuum of the storage ring
  (contamination and/or air inrush from the
  Beamline)
• protect the optical components of the beamline
  from possible contaminants (from the SR)
• dissipate all the unusable power generated from
  the light source in order to reduce the
  overheating of the BL optical components.

3
ID Front-end layout (ELETTRA) - Undulator section
8 -

• Diaphragm
• Photon Shutter
• Beam Stopper
• Fast Valve
• IMG
• IMG Pirani
• RGA
• Gate Valve
• Ion Pump
• Delay Line
• (Double Slits)
• (Photon BPM)
• Shielding Wall

(8)
(13)
(7)
(5)
(9)
(9)
(3)
(4)
(9)
(2)
(1)
(10)
(6)
4
BM Front-end layout (ELETTRA)

• Diaphragm (2 x 6mrad)
• Photon Shutter Beam Stopper
• Gate Valve
• Fast Valve
• IMG Pirani
• RGA
• Ion Pump

(1)
(2)
(5)
(3)
(4)
(6)
(7)
5
The Front-end Vacuum System _at_ ELETTRA
Insertion Device Front-end
Bending Magnet Front-end
Length 6 m IMG
2 Pirani gauge 1 Ion pump 230 l/s
3 NEG Pump 3 P lt 1 E-9 mbar (with
photons)
Length 11 m IMG
5 Pirani gauge 3 Ion Pump 230 l/s
5 NEG Pump 1 P lt 1 E-9 mbar (with
photons)
6
Front-ends _at_ ELETTRA
Light Port m.n m straight section number m
1 12 n light source type n 1
Bending Magnet n 2 Insertion Device ()
12.2 Bend. Magnet
7
Front-end vacuum faults _at_ ELETTRA (1993 2004)
8
Front-end vacuum system few (silly?)
questions. Pumping system Ion pump diode,
triode, Ti-Ta, Starcell are really so
different? Getter pump TSP, Neg cartridge or
coating. Do we need them? Fast valve system It
works, but it is expensive! Can we serenely live
without it? Vacuum Instrumentation IMG, RGA
where do we have to install them? RGA vacuum
monitoring or just for maintenance? Ancillary
subsystem Water flowmeters, position indicators
(microswitches), thermocouples, etc. are
potentially dangerous! Possible effects on the
interlock system (Beam dump!). Which strategies
to reduce their impact on the accelerator
operations? Reliability Do you adopt any
systematic preventive maintenance (bellows,
...)? Generally speaking Accordingly with your
experience, which are the weakest point (if any)
in a really used Front-end?
9
Fast valves _at_ ELETTRA

• Some facts
• 20 fast valves installed on 16 front-ends (VAT
  77, CF40-CF160)
• 1 front-end without fast valve (Infrared
  beamline)
• 5 ventings of the storage ring (SR) avoided in
  12 years
• 0 spurious closing (no sensor installed in the
  SR)
• 300 k spent in 9 years (1993 2001)
• 10 full days to recover from a complete venting
  of the SR (minimum!)
• 21 different experiments at the same time
• 50 users/day