www.chave.net 25-sep-02 pdr rev d cryo-cooler goniometer for arcs robust, low cost cryo-cooler...

25-Sep-02 PDR Rev D Cryo-Cooler Goniometer for ARCS www.chave.net

Robust, Low Cost Cryo-cooler Goniometer for ARCS

using available, commercial grade, instrument components

Preliminary Design Review

Prepared by Robert ChaveRobert Chave Applied Physics Inc.

Altadena, California

[email protected]


Design Approach

• A design which permits a range of options for sample mounting, and leaves opportunity for future modification for presently unspecified needs

• Selection and placement of materials so as to avoid signal to noise reduction through scattering or a radioactive waste problem

• Maximal use of off-the-shelf, or build-to-existing print major components to reduce cost both of primary build and availability of spares

• Separate motion controller, independent from data computer for increased reliability, communicating with data computer through IEEE488

• Integrated system of motion controller, stepper drivers, motors, software and cables from an “all in one box” vendor of motion control technology


Requirements / Goals

Goal:

Sample Temperature

Positioning accuracy

Vacuum

Rapid cool down

Reliability

Ease of use

Rapid pump down

Approach:

10 K to 290 K

6 arc minutes absolute, both axes

10-7 Torr

Less than 3/4 hour

Consistent with $1.4 Billion source cost

Ease of Sample Insertion & no binding on alignment pins

No virtual leaks, easy vacuum conductance


Design Trade Studies

Basic Configuration Trade Study

Cooler on center, mechanical & thermal paths combined, single large built-to-user-specification, seal-bearing unit.

Cooler off-center, mechanical & thermal paths separate, standard seal-bearing unit, located on instrument centerline.

Cooler on center, mechanical & thermal paths, separate, main bearing on center & in vacuum, smaller standard seal. ☼


Configuration Trade Study



Thermal Rotary Joint Trade Study

Slip joint

Conduction through mechanical flexure joint

Thermal strap of fully annealed, three thousand strand, thin-strand, copper Litz wire. ☼

Vacuum Condensable Materials Reduction Trade Study

Motors in and out of vacuum

Ferroseal vs O-rings

Lubricants, BraygreaseTM and DichroniteTM


Cryo-cooler Goniometer for ARCS

radiation shield

flexible Litz wire

sample mounting plate, aluminum

APD Sumitomo Cooler, 2 stage, 80 W max

thin section bearings

thin section isolation tube, G10 or SS

thin wall SS axle

ferrofluidic seal

Worm drive,180:1 ratio, no back-lash

drag link, w/ DelrinTM rod end bearings thin section, KaydonTM

bearing assemblies

stepper motor NEMA23, 2 stack

stepper motor NEMA17, vacuum type

harmonic drive, vacuum type

video camera


ARCS Goniometer & Vacuum Jacket



Thermal Isolation Performance Trade Study

SS down tube

G10 down tube

Vibration Susceptibility Trades Study

Fundamental Frequencies

Brace approach


Thermal Modeling

Isolation Links

SourcesoHeat capacity of structure during cool downoRadiation (small compared with above)

SinksoCooleroTop plate

System Sensitivities: The number and preparation of thermal joints drives cool downtimes, and lowest sample temperature attainable more strongly than other system parameters


Cryocooler & Thermal Isolation Structure

radiation shield

flexible Litz wire

sample mounting plate, aluminum

thin section bearings

thin section isolation tube,

G10 or SS

APD Sumitomo Cooler, 2 stage, 80 W maximum

tubular SS axle


Cooler Power APD 408S vs Cryotiger

SHI-APD 408 S• two stage• 80 Watts initial• final sample temp of 10 K• $ 27,800

IGC-CryoTiger• 1 hour to 100 K• 10 Watts initial• final sample temp of 77 K• $ 8,655 each unit


Cooler Performance & Conductor Performance

0 50 100 150 200 250 3000

100

200

300

400

Spec_Heat

Temp

conductivity integral for copper

0 50 100 150 200 250 3000

5 104

1 105

1.5 105

K

W/c

m

Cond_Int_Cu

Temp

cooler power

0 50 100 150 200 250 3000

20

40

60

80

100

K

Wat

ts

C_Pwr_Pgrm Temp i

Temp i

Specific Heat of Copper

image credit: Cooner Wire


Resistance of Thermal & Structural Elements

• the number of mechanical joints between source and sink and their state of preparation is an influential design parameter

• rougher surfaces are sometimes more effective than smooth ones• indium gaskets desirable on conductive joints

0 50 100 150 200 250 3000.01

0.1

1

10

100

1 103

1 104

K

1/W

att

Resistance_D_Tube 273 K Temp1( )

Resistance_Spoke 273 Temp1( )

Resistance_S_Contact 273 Temp1( )

Resistance_T_Contact 273 Temp1( )

Resistance_Litz_ 273 Temp1( )

Temp1


Isolation System – Steady State Temperatures

0 1 2 3 4 5 6 7 80

100

200

300

T_ssi

i

Down Tube G10

Spokes

Down Tube G10

Spokes

Litz Wire

Litz Wire

Sample

Sample

Bearing

Bearings


Cold End Thermal Isolation System

Spoke Properties• maximum heat flow ~ 550 mW • heat flow steady state < 50 mW• commercial product• titanium or stainless• low cost, high stiffness, readily available

0 100 200 3000

0.2

0.4

0.6

0.8

1

Temperature K

Full

Scal

e =

1 W

att

Q_spokes TempSS 7 K( )

TempSS


Mechanical Properties of Spokes

LFy L_Spoke

Area_Spoke E

L 0.019mm

Fundamental Frequency with Given Tip Mass Equal to MTip:

kwireFy

L

kwire 6.56 104

lbf

in Mtip 7 lb

_naturalkwire

Mtip _natural 1.9 10

3 Hz

Stress in Individual Spoke

s_spokeFy

Area_Spoke s_spoke 1.768 10

4

lbf

in2

Yield Stress in 301 Stainless, full hardness, per AIAA Handbook:

s_yield_301SS 185000lbf

in2

s_spoke

s_yield_301SS0.096

Factor_of_Safetys_spoke

s_yield_301SS

1

Factor_of_Safety 10.462

Fundamental freq: ~ 2 kHz

Factor of Safety: 10.5

Nom. Load per Spoke: 50 lbs

Diameter: 1.5 mm


Drive Train, 2 Axesstepper motor NEMA23, 2 stack, Compumotor

ferrofluidic seal

Worm drive,180:1 ratio, zero back-lash

drag link, w/ DelrinTM rod end bearings

thin section, KaydonTM bearing assemblies

drag link, w/ DelrinTM rod end bearings

stationary APD cooler head

sample mounting plate

stepper motor NEMA17, 2 stack, vacuum rated

harmonic drive, 30:1, zero back-lash


Expected Accuracy for Drive Train

Cumulative error of the various kinematic components is within the 1/10th degree specified by the Project as a goal.

Primary Axis Source Error

Accuracy of Parker Daedal Drive 3 arc minutes

Ball End Roundness Tolerance 1.2 arc minutes


Total Error, absolute 5.4 arc minutes

RMS Error 3.4 arc minutes

Secondary Axis Source Error

Accuracy of Harmonic Drive 1.5 arc minutes



Total Error, absolute 3.9 arc minutes

RMS Error 2.3 arc minutes


Harmonic Drive

Model CSF-17-30-2A-R w/ Vacuum Lube

Drive Ratio 30:1

Accuracy 1.5 arc minute

Max Peak Torque Load 266 in-lbs

Lubricant BraygreaseTM

flight rated NASA

image credits: HD Systems Inc.


Thermal & Motion Sensors & Limit Switches

Sensors

Hall effect for end of travel and home position sensing, in vacuum

Motor temperature for in-vacuum motor

End effector temperature sensing with Lake Shore silicon diodes

Control System Switch Configuration

Hard (switch) stops and soft (programmed) stops, with hard stops normally never encountered

Hard stops are wired directly to individual axis drive electronics

Peperol & Fuchs NBB 1.5 – 8 GM60


Motion Control Software

Test scripts in Python

Communication w/ Controller either by Ethernet, or serial cable

Controller software is "Motion Planner" TM by Compumotor

owell characterized, large installed user base, well supportedoPoint to point motion and calibration routines

oS-curve accelerations, to limit ringing in mechanical components, from acceleration and braking


Block Diagram, Drive Components


Video Camera

Video Camera for Sample in Vacuum Monitoring

COHU Camera, to special performance specification for LLNL

vacuum & radiation ratedproduction run of 1000 for LLNL reduces price

COHU 2600 b/w camera


Preventing Binding During Insertion


Virtual Leak Attenuation & Pump Down Speed

Methods Employed:

Fastener holes and tapped holes drilled through to back side of part, such that these vent freely

Use of center vented fasteners where back side vent ports are not practical

No enclosed volumes & easy vacuum conductance from partially enclosed volumes

Vapor degreasing, plus solvent cleaning to remove vacuum condensible material


Instrument Case, Storage & Transfer

• rapid instrument insertion• rapid instrument lock down• device cleanliness retained• fork lift o.k.• 3’ x 3’ x 3¼’ h


ReferencesPapers

Gimbal Mechanism For Cryogenic Alignment Of 1 Meter Diameter Optics, R. G. Chave, A. E. Nash, J. Hardy, SPIE Proceedings, 40th Annual Meeting, 1995

Handbook on Materials for Superconducting Machinery, ARPA order No. 2569, Program Code 4D10, Contract No. CST-8303, Cryogenics Division, NIST, 1977

Thermal Boundary Resistance of Mechanical Contacts Between Solids at Sub-Ambient Temperatures, E. Gmelin, M. Asen-Palmer, M. Reuther and R. Villar, Review Article, Journal of Physics D: Applied Physics 32 R19-R43, 1999.

Texts

Cryogenic Process Engineering, Timmerhaus & Flynn, Plenum Press, International Cryogenics Monograph Series, 1989

Experimental Techniques in Condensed Matter Physics at Low Temperatures, Richardson & Smith, Addison Wesley, 2nd Edition1998

Matter and Methods at Low Temperatures, F. Pobell, Springer Verlag 2nd Edition 1996


Budget - Purchased Parts

Description Vendor Type Qty $/ea ExtendedAPD Sumitomo Cooler, c head, cmprssr, 20M lines &tc Sumitomo Quote 1 27,800 27,800 Machined Parts Various Estimate pkg 17,500 Test Equipment and Fixtures Various Estimate pkg 8,000 Motors, T Table, Step Drives, Cables, P Supply, Software Parker Daedal Quote 1 7,352 7,352 Cryo Temp Sensor 8 channel w/ IEEE488 bus Lakeshore Quote 1 1,553 1,553 FerroFluidSeal SS500 SLFA Ferrotech Quote 1 1,302 1,302 Video Camera, Vacuum rate COHU 2600 LLNL COHU Quote 1 1,253 1,253 Diode Sensors DT6760-C-SD accuracy 1 K Lakeshore Quote 6 175 1,050 Harmonic Drive CSF-17-30-2AR HD Systems Quote 1 687 687 Kaydon Bearing KA055CPO Bearing Specialty Quote 2 339 678 Proximity Sensor, Hall Effect, Vacuum Rated any Estimate 3 100 300 Video Monitor & Cables any Estimate 1 300 300 Vacuum Feed Throughs & Special Vac Cable any Estimate 1 300 300 Kaydon Bearing KA030CPO Bearing Specialty Quote 2 148 296 Proximity Sensor, Hall Effect, NBB1.5-8GM60 Peperol & Fuchs Catalog 2 56 112 Newport Bracket 360-90 Newport Corp Quote 1 85 85 Lifting Rings, OSHA, Part No. 29505T21 McMaster-Carr Catalog 3 13 39 W ire Rope Crane Slings, OSHA, Part No. 3550T34 McMaster-Carr Catalog 3 12 35 Litz Wire Cooner Wire Quote 1 35 35 Ball Joint Delrin QTR_28 Small Parts Inc Small Parts Quote 6 5 32

sub total 68,709$


Budget – Cost to Complete

Puchased Parts, as detailed above 68,709 Engineering Detailed Design & Working Drawings not to exceed 10,000 Assembly & Test Labor, plus Basic Programming not to exceed 18,000

Total to First Delivered Unit 96,709$


Schedule to Completion

www.chave.net 25-sep-02 pdr rev d cryo-cooler goniometer for arcs robust, low cost cryo-cooler...

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