COMPRES Annual Meeting, Lake Morey, VM, June 17-20, 2007

Johnson Noise Thermometry at High Pressure

Yanbin WangTakeshi Sanehira

Ivan GettingMark Rivers

COMPRES Annual Meeting, Lake Morey, VM, June 17-20, 2007

Status• COMPRES support • Dr. Takeshi Sanehira on board since Dec 2006• Developing JNT cell• Testing new probe resistors• Identify noise sources and ground loop issues• Setup tests on transformers, variac, powerline filter • High P-T tests, Feb ~ Apr:

– Sanehira, Wang, Getting, Labenski (NIST; attempted to hire as a temp employee)

• First high P-T results to ~1000 K, 0.1-0.3 GPa

COMPRES Annual Meeting, Lake Morey, VM, June 17-20, 2007

16 mm cell design

COMPRES Annual Meeting, Lake Morey, VM, June 17-20, 2007

Ambient spectra before turning on AC power supply

COMPRES Annual Meeting, Lake Morey, VM, June 17-20, 2007

JNT connected to cell, supply turned on

Solution: fire cell parts at 900 – 1100 C, burn off all glue and organic residues

COMPRES Annual Meeting, Lake Morey, VM, June 17-20, 2007

-10

-8

-6

-4

-2

0

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4

6

8

10

0 200 400 600 800 1000 1200w/o Sloa

-10

-8

-6

-4

-2

0

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6

8

10

0 200 400 600 800 1000 1200

w/o Sloa

Synth

-10

-8

-6

-4

-2

0

2

4

6

8

10

0 200 400 600 800 1000 1200

w/o Sloa

Synth

w/ Sola

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0

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0 200 400 600 800 1000 1200

w/o Sloa

Synth

w/ Sola

Synth

Noise Reduction: Power Supply

Solution: replaced existing supply with a transformer and added a powerline conditioner (Sola) to ensure pure sinusoidal output at 60 Hz.

COMPRES Annual Meeting, Lake Morey, VM, June 17-20, 2007

Noise Reduction: high-frequency pickup

-90

-70

-50

-30

0 20 40 60 80 100

Thousands

18 kHz37 kHz 55 kHz 73 kHz 92 kHz

Solution: Shutoff all unused electronics inside the hutch. Eliminate ground loop by defining common ground.

COMPRES Annual Meeting, Lake Morey, VM, June 17-20, 2007

Noise reduction: 60-Hz harmonics

200 C

Solution: Apply numerical notch filters for 60 Hz (5 -10 Hz width). Apply a higher cutoff to the high-pass filter, throw away signals below 20 kHz.

COMPRES Annual Meeting, Lake Morey, VM, June 17-20, 2007

Test data

500 K

COMPRES Annual Meeting, Lake Morey, VM, June 17-20, 2007

Test data

800 K

COMPRES Annual Meeting, Lake Morey, VM, June 17-20, 2007

First high T measurements to 800 K:Resistance drop near 600 K

Probe Resistance vs. T

y = 5.0682299809E-02x + 3.4709431275E+01

30

35

40

45

50

55

60

65

70

75

80

0 100 200 300 400 500 600 700 800 900

Thermocouple Temperature (kelvins)

Pro

be

Re

sist

an

ce (

oh

ms)

N.C.

Linear (N.C.)

COMPRES Annual Meeting, Lake Morey, VM, June 17-20, 2007

JNT output versus Temperature

NC Normalized Output vs. T

y = 2.6181294173E-03x - 2.6088699166E-01

0.0

0.5

1.0

1.5

2.0

0 100 200 300 400 500 600 700 800 900

Thermocouple Temperature (kelvins)

NC

No

rma

lize

d O

utp

ut '

N.C.

Linear (N.C.)

COMPRES Annual Meeting, Lake Morey, VM, June 17-20, 2007

First high T resultsJNT versus RT

0

0.1

0.2

0.3

0.4

0.5

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0.9

1

1.1

1.2

1.3

1.4

1.5

1.6

1.7

1.8

1.9

2

2.1

2.2

0 10000 20000 30000 40000 50000 60000 70000

RT (ohm Kelvin)

JNT

ou

tpu

t

heating 2

heating 5

heating 1

heating 4

Bench

NC Normalized Output vs. RT

0

2

4

6

8

10

12

14

16

0 50 100 150 200 250 300 350 400

ThousandsSensor RT (ohm*kelvins)

NC

Norm

aliz

ed

Ou

tpu

t

N.C.

Poly. (N.C.)

COMPRES Annual Meeting, Lake Morey, VM, June 17-20, 2007

Future plans• Noise reduction!!• New filters for JNT (expand frequency range to 100

kHz, vs. 70 kHz) - ordered• New transformer – received• 16 mm cell for “zero P” calibration• Smaller cells and truncations for higher P

measurements• Beamtime proposal for 2007-3 (measure P using

diffraction)• New resistors

– Cermets versus sintered diamond• Pyrometry cross-check