PEEM III Endstation Design Review Endstation Layout Support System Vessel Magnetic Shielding

PEEM III Endstation Design Review

Endstation LayoutSupport System Vessel Magnetic Shielding


Endstation Layout Sector 11


Endstation Layout


MicroscopeSample Prep and transferGeneral HV UHV in Sample and Mirror Sections

< 2x10-7 Gauss AC Field

Nanometer Scale Stability-Sample to Optics

Easy access to internal components


Microscope - Details5-Axis Sample ManipulatorFiber-Optic Laser90 degree Optics and MirrorInternal SupportCCD CamerasUHV Sub-ChamberSeparator Replacement Optics


Support SystemHigh stiffness - vibration isolated internal supportSemi-kinematic mountingEpoxy-granite filled baseVisco-elastic dampingIsolated chamber and external components


Support System - AssemblyInstall/Align base stand with visco-elastic damping padsInstall/align filled baseSide mounting pads for jacks/ball platesMount internal table support legs and align fiducialized table (or plate)Install/align struts and chamber


Vacuum Vessel


Vacuum Vessel - DetailsHV required UHV desirableSS plate weldment Differentially pumped, double o-ring, window frame to lid sealStandard conflat ports


UHV Sub-Chamber - DetailsAluminum conductance limited UHV-HV sub-chambersO-Ring base/lid sealGlass viewing windowBe-Cu sheet interface


UHV Sub-Chamber - Details

Table 5. Gas loading on the Main Peem3 chamber and pressure after 100 hours with 10" OD tee pumping system, 800 l/s ion pump + 1000 l/s turbo

Main PEEM3 vacuum tankOutgassing rate 100hrsAreaGas loadfraction torr l/s/cm^2cm^2torr l/s%Al tank 1.00E-10335003.35E-064Mu metal 1.00E-102032252.03E-0527Al optic table1.00E-1050005.00E-071Separator magnet1.00E-1035003.50E-070Epoxy Castal E301-KT,RT752.56E-071734.43E-0559kapton wires1.00E-0920002.00E-063Viton O-ring double (cm)3.00E-103009.00E-080Viton O-ring 20 KF40(cm)1.80E-082514.52E-066Total outgas rate7.54E-05torr l/sMain tank pump l/s880.95Pressure in main tank torr8.56E-08torr

Main microscope tankMu metal Stove PipeUHV sub-chamberMainPumpingTeeMainPumpingAdaptorTurboValveIon Pump 1Ion Pump 2MainPumpingBellowsHole for electronsCu/Be rolled sheetUHV Pump TeeUHV Pump bellows Schematic arrangement of Peem3 pumping for UHV sub-section and main tank Window

Table 7. Gas loading on the UHV sub-chamber and pressure after 100 hours with 8" OD tee pumping system and 800 l/s ion pump. Pressure in main tank = 8.5e-8 torr.

Sub UHV chamberBox 20x20x20cm - 1/2" Al plate with viton O ring sealsOutgassing rate 100hrsAreaGas loadfraction torr l/s/cm^2cm^2torr l/s%Al sub chamber tank 1.00E-1024002.40E-0736Lenses 5.00E-101809.00E-0814Ceramic 2.30E-101804.14E-086Sample manipulator2.30E-104009.20E-0814Viton O-ring (cm) baked 3.00E-102407.20E-0811Total outgass rate5.35E-0781Leaks from main tankarea cm^2length cmConductance l/s25um gaps in overlap sleeve walls0.251.21.12038(2x4" and 3x1.5" sleeves)2mm Aperture for electrons0.031400.36688total leak conductance1.48726l/sGas load of leak torr l/s1.27E-0719Total gas load 6.63E-07100UHV sub-ch pump l/s269.65l/sP in UHV sub-cham torr2.46E-09torr


Magnetic Shielding

Magnetic Shielding requirements require < 2x10-7 Gauss ACAC field on the floor of +-0.3mGauss (1Hz) Need attenuation of ~ 2500 Crude cylinder model indicate 2 layers attenuate ~16003 layers attenuate ~ 26000Better calculation by Amuneal suggest 3 layer attenuation ~ 7000Thickness of shield = 3mm for mechanical rigidity Shield spacing = 25mm as large as possible given space constrainsDegaussing of inner shield with AC and internal coils

Magnetic field at Peem3 locationModel of mu metal shields with Vacuum chamberremoved


Magnetic Shielding3 Concentric boxes with ~ 1 gapAssembled from outside inSeparated with aluminum spacers/handle mountsPEM fasteners @ ~3.5 spacingNo penetrations > 5 diameters in critical areas - tubulations~ 3 diameters in 2 pump sections


Magnetic ShieldingTubulation Details


The End (Hopefully)

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PEEM III Endstation Design Review Endstation Layout Support System Vessel Magnetic Shielding