Laboratory of Metrology and QualityFaculty of Electrical EngineeringUniversity of Ljubljana

MIRS/FE-LMK

Design And Construction Of The Gallium Melting

PointJovan Bojkovski, Miha Hiti, Valentin

BatageljEUROMET 732 project, WP 5

MIRS/FE-LMK24.11.2006

Laboratory of Metrology and QualityFaculty of Electrical EngineeringUniversity of Ljubljana

MIRS/FE-LMK

Summary

• Activities so far– Design– Material– Cleaning process– Filling process– Testing

• Future activities– Analysis of the material– Analysis of the design and its influences– Intercomparison with other laboratories

(SMU, ...)

Laboratory of Metrology and QualityFaculty of Electrical EngineeringUniversity of Ljubljana

MIRS/FE-LMK

Design (1)

• “Classical” design (YSI, Isotech, ...)• So-called virgin teflon as basis for

enclosure and thermometer well• Only two parts decrease of possible

leakage• Inside and outside aluminium tube in order

to increse radial heat transfer• Dimmensions same as commercial

possibility to realize it inside special furnace

Laboratory of Metrology and QualityFaculty of Electrical EngineeringUniversity of Ljubljana

MIRS/FE-LMK

Design (2)

•30 cm length•3,5 cm width•Thickness of the walls 2 mm•Immersion depth 20 cm

Laboratory of Metrology and QualityFaculty of Electrical EngineeringUniversity of Ljubljana

MIRS/FE-LMK

Material (1)

• Nominally > 7 N purity• Source of material China (Guangzhou

Youyuan Metals & Chemicals Co.,Ltd.)• Very cheap material risk of getting

material of poor quality– 1 kg of Ga = 700 $– 1 kg of Zn = 780 $

• However, we didn’t have any experience high possibility of errors and contamintion of better and more expensive gallium

Laboratory of Metrology and QualityFaculty of Electrical EngineeringUniversity of Ljubljana

MIRS/FE-LMK

Material (2)

Laboratory of Metrology and QualityFaculty of Electrical EngineeringUniversity of Ljubljana

MIRS/FE-LMK

Cleaning process (1)

• Dry cleaning to eliminate any leftovers from machining process

• Cleaning with mild detergent• Cleaning with pure alcohol• Cleaning with double destilled water• Ultrasonic cleaning with destilled

water

Laboratory of Metrology and QualityFaculty of Electrical EngineeringUniversity of Ljubljana

MIRS/FE-LMK

Cleaning process (2)

Laboratory of Metrology and QualityFaculty of Electrical EngineeringUniversity of Ljubljana

MIRS/FE-LMK

Filling process (1)

• It has been filled inside dry-box• Known concentration of water vapour

(< 20 ppm) and oxygen (<1 ppm) inside the dry-box

• Material melted and filled to the teflon container and closed inside controlled atmosphere

Laboratory of Metrology and QualityFaculty of Electrical EngineeringUniversity of Ljubljana

MIRS/FE-LMK

Filling process (2)

Laboratory of Metrology and QualityFaculty of Electrical EngineeringUniversity of Ljubljana

MIRS/FE-LMK

Testing

• Only part of testing has been made• First stage is direct comparison to

the reference cell used in EUROMEt 552.K3

• Realization inside different thermal enclousers

• Difference from reference cell is +40 microK

Laboratory of Metrology and QualityFaculty of Electrical EngineeringUniversity of Ljubljana

MIRS/FE-LMK

28,57892

28,57897

28,57902

28,57907

28,57912

28,57917

28,57922

17.12.200310:00

17.12.200312:00

17.12.200314:00

17.12.200316:00

17.12.200318:00

17.12.200320:00

17.12.200322:00

18.12.20030:00

18.12.20032:00

18.12.20034:00

date and time

resi

stan

ce

in o

hm

s

0,5 mK

Reference cell

Laboratory of Metrology and QualityFaculty of Electrical EngineeringUniversity of Ljubljana

MIRS/FE-LMK

Stability of resistor bath

22,998

22,999

23

23,001

23,002

23,003

23,004

23,005

13.1.200412:36

13.1.200415:00

13.1.200417:24

13.1.200419:48

13.1.200422:12

14.1.20040:36

14.1.20043:00

14.1.20045:24

14.1.20047:48

14.1.200410:12

14.1.200412:36

date and time

tem

per

atu

re in

°C

Laboratory of Metrology and QualityFaculty of Electrical EngineeringUniversity of Ljubljana

MIRS/FE-LMK

New cell results (1)

28,417

28,41705

28,4171

28,41715

28,4172

28,41725

28,4173

28,41735

28,4174

18.10.2006 15:27 18.10.2006 20:15 19.10.2006 1:03 19.10.2006 5:51 19.10.2006 10:39 19.10.2006 15:27

date and time

resi

stan

ce

in o

hm

s

0,5 mK

Laboratory of Metrology and QualityFaculty of Electrical EngineeringUniversity of Ljubljana

MIRS/FE-LMK

New cell results (2)

28,4171

28,41712

28,41714

28,41716

28,41718

28,4172

28,41722

28,41724

28,41726

28,41728

28,4173

18.10.200615:46

18.10.200615:48

18.10.200615:51

18.10.200615:54

18.10.200615:57

18.10.200616:00

18.10.200616:03

18.10.200616:06

18.10.200616:09

18.10.200616:11

date and time

resi

stan

ce

in o

hm

s

0,2 mK

Laboratory of Metrology and QualityFaculty of Electrical EngineeringUniversity of Ljubljana

MIRS/FE-LMK

New cell results (3)

0

0,00002

0,00004

0,00006

0,00008

0,0001

0,00012

0 1 2 3 4 5 6 7 8 9

distance from the bottom in cm

tem

pe

ratu

re d

iffe

ren

ce

in K

Laboratory of Metrology and QualityFaculty of Electrical EngineeringUniversity of Ljubljana

MIRS/FE-LMK

Problems

• Long response time– Thickness of teflon ?

• Repeatable decrese at the beginning of the plateau– Material composition

• “Short-circuit” of the material thermometer is influenced by the furnace

• ......

Laboratory of Metrology and QualityFaculty of Electrical EngineeringUniversity of Ljubljana

MIRS/FE-LMK

Further activities

• Analysis of the material• Analysis of the design and its

influences• Intercomparison with other

laboratories (SMU, ...)• Building new cells from existing

material• Buying new material if necessary