PEEM III Endstation Design Review

PEEM III Endstation Design Review

• Endstation Layout• Support System • Vessel • Magnetic Shielding


Endstation Layout – Sector 11


Endstation Layout


MicroscopeSample Prep and transfer

General HV – UHV in Sample and Mirror Sections

< 2x10-7 Gauss AC Field

Nanometer Scale Stability-Sample to Optics

“Easy” access to internal components


Microscope - Details

5-Axis Sample Manipulator

Fiber-Optic Laser

90 degree Optics and Mirror

Internal Support

CCD Cameras

UHV Sub-Chamber

Separator Replacement Optics


Support System

High stiffness - vibration isolated internal support

•Semi-kinematic mounting

•Epoxy-granite filled base

•Visco-elastic damping

•Isolated chamber and external components


Support System - AssemblyInstall/Align base stand with visco-elastic damping pads

Install/align filled base•Side mounting pads for jacks/ball plates

Mount internal table support legs and align fiducialized table (or plate)

Install/align struts and chamber


Vacuum Vessel


Vacuum Vessel - Details

HV required – UHV desirable

SS plate weldment

Differentially pumped, double o-ring, window frame to lid seal

“Standard” conflat ports


UHV Sub-Chamber - Details

Aluminum conductance limited UHV-HV sub-chambers

•O-Ring base/lid seal

•Glass viewing window

•Be-Cu sheet interface


UHV Sub-Chamber - Details

Main PEEM3 vacuum tank

Outgassing rate 100hrs Area Gas load fraction

torr l/s/cm^2 cm^2 torr l/s %

Al tank 1.00E-10 33500 3.35E-06 4

Mu metal 1.00E-10 203225 2.03E-05 27

Al optic table 1.00E-10 5000 5.00E-07 1

Separator magnet 1.00E-10 3500 3.50E-07 0

Epoxy Castal E301-KT,RT75 2.56E-07 173 4.43E-05 59

kapton wires 1.00E-09 2000 2.00E-06 3

Viton O-ring double (cm) 3.00E-10 300 9.00E-08 0

Viton O-ring 20 KF40(cm) 1.80E-08 251 4.52E-06 6

Total outgas rate 7.54E-05 torr l/s

Main tank pump l/s 880.95

Pressure in main tank torr 8.56E-08 torr

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 microscope tank

Mu metal Stove Pipe

UHV sub-chamber

MainPumping

TeeMain

PumpingAdaptor

Turbo

Valve

Ion Pump 1Ion Pump 2

MainPumpingBellows

Hole for electronsCu/Be rolled

sheet

UHV Pump Tee

UHV Pump bellows

Schematic arrangement of Peem3 pumping for UHV sub-section and main tank

Window

Sub UHV chamber Box 20x20x20cm - 1/2" Al plate with viton O ring seals

Outgassing rate 100hrs Area Gas load fraction

torr l/s/cm^2 cm^2 torr l/s %Al sub chamber tank 1.00E-10 2400 2.40E-07 36Lenses 5.00E-10 180 9.00E-08 14Ceramic 2.30E-10 180 4.14E-08 6Sample manipulator 2.30E-10 400 9.20E-08 14Viton O-ring (cm) baked 3.00E-10 240 7.20E-08 11

Total outgass rate 5.35E-07 81

Leaks from main tank area cm^2 length cmConductance l/s

25um gaps in overlap sleeve walls 0.25 1.2 1.12038

(2x4" and 3x1.5" sleeves)

2mm Aperture for electrons 0.0314 0 0.36688

total leak conductance 1.48726 l/s

Gas load of leak torr l/s 1.27E-07 19

Total gas load 6.63E-07 100

UHV sub-ch pump l/s 269.65 l/s

P in UHV sub-cham torr 2.46E-09 torr

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.


Magnetic Shielding

Magnetic Shielding requirements

- require < 2x10-7 Gauss AC-AC field on the floor of +-0.3mGauss (1Hz)- Need attenuation of ~ 2500- Crude cylinder model indicate

-2 layers attenuate ~1600-3 layers attenuate ~ 26000

-Better calculation by Amuneal suggest 3 layer attenuation ~ 7000-Thickness of shield = 3mm for mechanical

rigidity- Shield spacing = 25mm – as large as possible given space constrains-Degaussing of inner shield with AC and

internal coils

Magnetic field at Peem3 location

Model of mu metal shields with Vacuum chamberremoved


Magnetic Shielding

3 Concentric boxes with ~ 1’’ gap

Assembled from outside – in

Separated with aluminum spacers/handle mounts

PEM fasteners @ ~3.5” spacing

No 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