Changes between Version 35 and Version 36 of SavinGroup/MergedBeams/EndSection
- Timestamp:
- 10/08/09 14:50:33 (17 years ago)
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SavinGroup/MergedBeams/EndSection
v35 v36 18 18 19 19 == Energy Analyzer == 20 [[br]] [[br]]20 [[br]] 21 21 The H,,2,,^+^ is seperated from the rest of the stream by an electrostatic energy analyzer. The intial H^-^ ions typically have energies of 10 keV, so an H,,2,,^+^ molecule has 20 keV and is easily seperated. 22 22 23 23 == Channeltron Electron Multiplier == 24 [[br]] [[br]]24 [[br]] 25 25 26 26 After the H,,2,,^+^ is seperated it is counted by a Channeltron Electron Multiplier (CEM). The CEM has a conical opening leading to a serpentine shaped tunnel. The insides of the cone and tunnel are coated with lead glass material. When a potenial difference is applied across this tunnel, incident particles will crash into the walls, splashing off electrons. The electrons pinball their way through the tunnel gaining more electrons everytime they hit the walls. This electron avalanche pinballs its way through until it hits the channel end anode where the pulse of electrons is measured. … … 34 34 splashed off by H atoms crashing into a collision plate. The plate is within a tube which will have a positive potential 35 35 on it (+300-400 V). The secondary electrons are sucked onto this tube and the resulting positive current is read off of 36 the collsion plate. The postitive electrode tube has to be protected by the incident beam, so a grounded shielding tube protects the 36 the collsion plate. The postitive electrode tube has to be protected by the incident beam, so a grounded shielding tube protects the 37 37 postive tube from the beam. The cup must be calibrated because with different vacuum conditions the amount of electrons that come off 38 38 of the collision plate can change. All parts were made of stainless steel.
