A New Coaxial Flow Calorimeter - NCSL International - …€¦ · · 2014-12-30A New Coaxial Flow...

A New Coaxial Flow Calorimeterfor Accurate RF Power Measurements

up to 100 Watts and 1 GHz

Andrew S. Brush

Jefferson D. Lexa

Motivation

• Decrease uncertainty of working standards at 100 Watts from 1 MHz to 1 GHz, from 2% to 1%

• Decrease labor involved in maintaining working standards.

Bramall Cascaded Couplers

Existing Method

• Uncertainty of approximately 1.5%• Uses banded couplers or manually

tuned couplers.• Tedious steps of stepping to 50 dB

coupling ratio.

Calorimeter Block Diagram

Error Sources

• Effective Efficiency• Reflection vs. Frequency• Thermal leaks• Thermopile nonlinearity• Flow Meter Error• Coolant Properties• Instrumentation error • Time shifting errors

RF efficiency modelNote: Enter "0" for line length if section not used

dielectric constant 2.05 2.05 1 1 2.05 2.05 2.05 2.054.61038E-13 Farads/in 4.61038E-13 Farads/in 2.24897E-13 Farads/in 2.24897E-13 Farads/in 4.61038E-13 Farads/in 4.61038E-13 Farads/in 4.61038E-13 Farads/in 4.61038E-13 Farads/in

permeability 1 1 1 1 1 1 1 13.19176E-08 Henries/in 3.19176E-08 Henries/in 3.19176E-08 Henries/in 3.19176E-08 Henries/in 3.19176E-08 Henries/in 3.19176E-08 Henries/in 3.19176E-08 Henries/in 3.19176E-08 Henries/in

conductivity of metal 6.29E+07 mhos/m 6.29E+07 mhos/m 6.29E+07 mhos/m 6.29E+07 mhos/m 6.29E+07 mhos/m 6.29E+07 mhos/m 6.29E+07 mhos/m 6.29E+07 mhos/m1.60E+06 mhos/in 1.60E+06 mhos/in 1.60E+06 mhos/in 1.60E+06 mhos/in 1.60E+06 mhos/in 1.60E+06 mhos/in 1.60E+06 mhos/in 1.60E+06 mhos/in

inner conductor radius 0.1181 in 0.09 in 0.284 in 0.25 in 0.1181 in 0.1181 in 0.1181 in 0.1181 inouter conductor radius 0.39 in 0.291 in 0.655 in 0.576 in 0.2756 in 0.2756 in 0.2756 in 0.2756 ininput line length 0.4 in 0.327 in 0.095 in 0.75 in 0 in 0 in 0 in 0 inloss tangent of dielectric 0.00015 0.00015 0.00015 0.00015 0.00015 0.00015 0.00015 0.00015

alpha0 4.76E-10 4.76E-10 3.33E-10 3.33E-10 4.76E-10 4.76E-10 4.76E-10 4.76E-10

Power at input Power at higher than calorimetercalorimeter lower than

section 1 section 2 section 3 section 4 section 5 section 6 section 7 section 8 alpha total alpha total RF efficiency measured input meas.frequency (MHz) frequency (Hz) rad/sec alphaT (dB) alphaT (dB) alphaT (dB) alphaT (dB) alphaT (dB) alphaT (dB) alphaT (dB) alphaT (dB) (dB) % % factor factor

10 10000000 62831853.07 5.02873E-05 5.46315E-05 5.57044E-06 4.96759E-05 0 0 0 0 0.000160165 0.00% 99.9963% 1.0000 1.000020 20000000 125663706.1 7.22804E-05 7.82117E-05 8.07079E-06 7.17759E-05 0 0 0 0 0.000230339 0.01% 99.9947% 1.0001 0.999930 30000000 188495559.2 8.96184E-05 9.66832E-05 1.0066E-05 8.93391E-05 0 0 0 0 0.000285707 0.01% 99.9934% 1.0001 0.999940 40000000 251327412.3 0.000104547 0.00011251 1.17998E-05 0.000104554 0 0 0 0 0.000333411 0.01% 99.9923% 1.0001 0.999950 50000000 314159265.4 0.000117935 0.000126647 1.33665E-05 0.000118268 0 0 0 0 0.000376217 0.01% 99.9913% 1.0001 0.999960 60000000 376991118.4 0.00013023 0.000139584 1.48145E-05 0.000130915 0 0 0 0 0.000415544 0.01% 99.9904% 1.0001 0.999970 70000000 439822971.5 0.000141696 0.000151611 1.61725E-05 0.000142755 0 0 0 0 0.000452235 0.01% 99.9896% 1.0001 0.999980 80000000 502654824.6 0.000152505 0.000162918 1.74594E-05 0.000153956 0 0 0 0 0.000486838 0.01% 99.9888% 1.0001 0.999990 90000000 565486677.6 0.000162779 0.000173636 1.8688E-05 0.000164633 0 0 0 0 0.000519736 0.01% 99.9880% 1.0001 0.9999100 100000000 628318530.7 0.000172603 0.000183862 1.9868E-05 0.000174873 0 0 0 0 0.000551206 0.01% 99.9873% 1.0001 0.9999200 200000000 1256637061 0.000255732 0.000269531 3.00275E-05 0.000262544 0 0 0 0 0.000817835 0.02% 99.9812% 1.0002 0.9998300 300000000 1884955592 0.00032414 0.000339045 3.85896E-05 0.000335868 0 0 0 0 0.001037643 0.02% 99.9761% 1.0002 0.9998400 400000000 2513274123 0.000384928 0.000400197 4.6325E-05 0.000401766 0 0 0 0 0.001233216 0.03% 99.9716% 1.0003 0.9997500 500000000 3141592654 0.000440847 0.000456005 5.3532E-05 0.000462917 0 0 0 0 0.0014133 0.03% 99.9675% 1.0003 0.9997600 600000000 3769911184 0.000493306 0.000508016 6.03636E-05 0.000520697 0 0 0 0 0.001582383 0.04% 99.9636% 1.0004 0.9996700 700000000 4398229715 0.000543145 0.000557151 6.69109E-05 0.000575923 0 0 0 0 0.001743129 0.04% 99.9599% 1.0004 0.9996800 800000000 5026548246 0.000590908 0.000604009 7.3233E-05 0.000629126 0 0 0 0 0.001897276 0.04% 99.9563% 1.0004 0.9996900 900000000 5654866776 0.000636976 0.000649005 7.9371E-05 0.000680676 0 0 0 0 0.002046028 0.05% 99.9529% 1.0005 0.9995

1000 1000000000 6283185307 0.000681623 0.000692443 8.53551E-05 0.000730843 0 0 0 0 0.002190265 0.05% 99.9496% 1.0005 0.99952000 2000000000 12566370614 0.001080305 0.001074374 0.000140009 0.001185927 0 0 0 0 0.003480615 0.08% 99.9198% 1.0008 0.9992

Section 5 Section 6 Section 7 Section 8Section 1 Section 2 Section 3 Section 4

• Enables assessment of RF losses in load that do not heat the water

• Allows up to 8 geometrical configurations

• We are using a constant = .9995 for 1 GHz currently based on best guess of RF load geometry

• Significant factor for > 1GHz

RF Load VSWR characterization

EXPIRATION DATE: 03/12/13DATA FILE TYPE: SENSORCorrections data for load # 5710

2-SIGMAFREQUENCY(MHZ) CALFACTOR % UNCERTAINTY(%) S11MAG(RHO) S11PHASE(DEG)

---------------- ------- ---------------- ------------- ---------------50 100 2.5 0.0238 173.44 -32.4760 100 2.5 0.0239 172.81 -32.4370 100 2.5 0.0238 170.83 -32.4780 100 2.5 0.0238 169.39 -32.4790 100 2.5 0.0238 168.27 -32.47

100 100 2.5 0.0238 166.97 -32.47150 100 2.5 0.0238 160.13 -32.47200 100 2.5 0.024 153.15 -32.40250 100 2.5 0.0244 146.43 -32.25300 100 2.5 0.0249 140.22 -32.08350 100 2.5 0.0252 134.88 -31.97400 100 2.5 0.0253 129.18 -31.94450 100 2.5 0.0256 123.09 -31.84500 100 2.5 0.026 117.65 -31.70550 100 2.5 0.0261 112.62 -31.67600 100 2.5 0.0261 106.83 -31.67650 100 2.5 0.0266 101.24 -31.50700 100 2.5 0.0269 96.72 -31.40750 100 2.5 0.0268 91.86 -31.44800 100 2.5 0.027 86.64 -31.37850 100 2.5 0.0273 82.6 -31.28900 100 2.5 0.027 78.65 -31.37950 100 2.5 0.0269 73.72 -31.401000 100 2.5 0.0271 69.8 -31.34

• RF load characterized to determine trans. coefficient

• Data embedded in firmware for RF calibration

• Models developed for VSWR assessment 60 Hz Surface Current Density

Thermopile characterization• Thermopile

characterized to determine Seebeck coefficient (Volts/deg K) needed for system algorithm

• Flow and thermal models utilized to determine pressure loss and heat distribution parameters

Ambient’s Role in offset power

Calibration standard & AC source

• Cal standard and AC source procured

• Extremely steady & repeatable

• Fully programmable for phase 3 tasks

Radian RD-23

Agilent 6811B

Acopian 24WB210 Power Supply +24 VDC

@ 2.1 A

Acopian 5EB50 Power Supply +5 VDC @ 500ma

120 VAC60 Hz

120 VAC

AC ON/OFFSwitch

Relays Tyco #K10P-11DT5-24

Interlock connector

Power SupplyPush to reset

Relay

Relay

+24 VDC

+5 VDC

Rev 1.0Thursday, 12/1/11

12/1/2011Proposed new block diagram

Tegam, Inc

Emerson Motor #S55JXNSR-7299

ProCon Pump #101A125F11BB130

Coolant Reservoir

NMB 4715MS-12TB10 Fan

Thermopile module

See through Level Meter

Temp Switch indicator

Low flow indicator

Signal Processor

RF Power Display

Max

Min

PID Controller Omega #CN13253-

DC

Facility water inlet

Facility water outlet

Temp Sensor

ASCO Solenoid Value

CompensatedFlowmeter

Heat Exchanger SWEP #B5H

DrainTemp ControlPush to reset

+120 VAC

+120 VAC

+24 VDC

120 VAC

+24 VDC

+5 VDC

Polyscience Chiller model #1186

Flow adjust

Lines either physically shortened or compensated

for thermal losses

RF POWER TO BE MEASURED

Liquid Cooled RF Load Bird #5710

Liquid temp sensor (RTD)

delta T

absolute T

New flowmeter

New signal proc. PCB

& algorithms

RF mismatch

constants

Temp sensor

Phase 1 Modified Block Diagram

Flow constriction

Calorimetric System AlgorithmThermopileADC output

RTDADC output

Calculate absolute T of heated water

Flowmeterfrequency output

ThermistorADC output

Calculate delta T

Calculate absolute T of ambient air

Measure DC

resistance of RF load

Convert to trans. loss

factor

Calculate cal factor+ Offset

Calculate input power

Display AC calibrated

power

frictional watts

Load efficiency

factor

Convert to mass

flowrate

Convert to flow

volume

Calculate flowrate

Apply K factor f(u)

measure pulses/sec

Calculate RF

calibrated power

Display RF calibrated

power

Read Calibrated AC power

from Radian

Store cal factors vs. power level

Measure ref. coef. vs. freq of RF load

analytic estimate-calculate waterflow

temp loss

Calculate specific gravity of water

Calculate specific heat of water

Calculate viscosity of water

ADC counts

T

ADC counts vs. Temp Table

ADC counts

T

ADC counts vs. Temp Table

V

T

Seebeck Coefficient Table

s.g.

T

Specific gravity vs. Water Temp Table

T

T

Air temp vs. Water Temp Table

P

cal

cal factor vs. power TableT

s.h.

Specific Heat vs. Water Temp Table

7/12/2012Calorimetric Algorithm

Tegam, Inc

Rev 1.1Friday, 7/13/12

A

A

(C)

(C)

(C)

(J/g-C)

(g/cm3)

T

u

Viscosity vs. Water Temp Table

(g/sec)

(watts)

(watts)

(watts)

(C)

(mPa-sec)

(GPM) (cm3/sec)

(watts) (watts)

(watts)

(ohms)

(rho)

Denotes future capability

User defined frequency

input variable

Analytic estimate-RF efficiency factor of RF load vs. freq

eff.

f

RF eff. vs. freq Table

(dimensionless)

(dimensionless)

(dimensionless)

(dimensionless)

(Calibration Procedure)



RF trans. loss factor of RF load vs. freq

(dimensionless)

trans loss

f

trans loss vs. freq Table

f

p

p vs. frequency Table

Denotes calibration procedure items

analytic estimate analytic estimate

ADC ref output

1

2

3

4

5

6

7

8

9 10 11

13 14

15

12

20

21

19

22

27

26

2425

23

18

16

17

(pulses/liter)

Serial number of RF load

ADC counts vs. voltage Table

V

ADC counts

28

Number of segments

Calculate voltageoutput from thermopile (V)

T

P

Air temp vs. Power 29

Calculate poweroffset from Ambient reading

(watts)

T pivot

Power KNew

Auto AC Calibration Block Diagram

Calibration Algorithm

Radian Power Readings in WattsReference standard

Calorimeter Power in

watts

Offset = bns

0 100

100Linear regression best

fit line n = 1, s = 1

Linear regression best fit line n = 10, s = 1..10

Segment 1

Segment 2

Segment 3

Segment 4

Segment n

X = (y – bns)/ mns (during measurement)

Y

X

Y = mns x + bns (during calibration)

Dataset x10, y10

System .ini files;[ReflectiveCoef]50=0.023860=0.023970=0.023880=0.023890=0.0238100=0.0238150=0.0238200=0.024250=0.0244300=0.0249350=0.0252400=0.0253450=0.0256500=0.026 550=0.0261600=0.0261650=0.0266700=0.0269750=0.0268800=0.027 850=0.0273900=0.027 950=0.02691000=0.02711050=0.0266

;

[Version]=1.1,061812

[RFLoadSerialNumber]=5710;[UserDefinedFreq]=1000;[DCLoadResistance]=47.6;[SeebeckCoef]; At this time a table can not be used since the calculation uses 1/SeebeckCoef=0.0425;[LoadEfficiencyFactor]=0.995;[RFPressureDrop]=15.248;[TotalPressureDrop]=17.83;[WaterFlowTempLoss]=0.0017;[Viscosity]=1.0;[KFactor]=8000;[RFEfficiencyFactor]=0.9995;[DF_FLOWMETER]=7.0;[DF_THERMISTOR]=4.0;[DF_RTD_PRE]=4.0;[DF_RTD_POST]=4.0;[DF_THERMOPILE]=6.0;[T_PIVOT]=26.11;[T_POWER]=0.4435;

[CalibrationFactor]12.8=1.008,2.75222.9=1.009,2.73832.9=1.008,2.75943.1=1.011,2.68753.1=1.013,2.58863.4=1.013,2.57373.4=1.005,3.05883.6=1.016,2.27793.8=1.013,2.566103.8=1.015,2.329

Relection.ini

Characterization.ini

Calibration.ini

Calorimeter Error Budget

Sources of UncertaintyCalorimeter Uncertainty Type Estimate (in %) Probability Distribution Divisor Standard Uncertainty (in %)

waterflow heat loss Type B 0.05 Normal 2.00 0.0250temperature uncertainty Type B 0.10 Normal 2.00 0.0500

AC Source stability Type B 0.30 Rectangular 1.73 0.1732calibration standard Type B 0.01 Normal 2.00 0.0050Flowmeter repeatability Type B 0.10 Normal 2.00 0.0500waterflow friction heating Type B 0.20 Normal 2.00 0.1000pump flow instability Type B 0.01 Rectangular 1.73 0.0058

RF LoadMismatch between AC and RF (reflection losses) Type B 0.05 U-shaped 1.41 0.0354Load efficiency Type B 0.01 Rectangular 1.73 0.0058RF efficiency Type B 0.05 Rectangular 1.73 0.0289Measurement Repeatability due to connector wear Type B 0.01 Normal 2.00 0.0050

Measurement UncertaintyCombined Uncertainty (%) Root Sum Squared 0.2187Expanded Uncertainty (%) Coverage Factor (K) 2 Measured Value ± 0.44Expanded Uncertainty (dB) Coverage Factor (K) 2 0.02 -0.02

Model 1311

A New Coaxial Flow Calorimeter - NCSL International - …€¦ · · 2014-12-30A New Coaxial Flow...

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