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Measurements of the Brazed Assembly

The assembly was brazed and the feedthroughs were fitted with dowel pins and vacuum seals. The following measurements were then made.

Position Cavity

poscav.png

Measurement results

Coupler QL QL,shorts Qext,min Qext,max Qext,median
1 198 267 383 766 575
2 191 236 501 1002 751
3 209 269 469 937 703
4 193 293 282 565 424
Average 198 613

The internal quality factor is therefore 292.

Comparison

Parameter Before brazing After brazing
f0/GHz 14.993 15.012
QL 224 198
Q0 306 292

Reference Cavity

refcav.png

Coupler QL QL,shorts Qext,n
5 128 191 388
6 131 189 427
Average 130 Qext 203

The internal quality factor is therefore 357.

Comparison

Parameter Before modification After modification After brazing
f0/GHz 16.940 14.960 14.997
QL 153 74 130
Q0 343 - 357

Temperature Stability of both Cavities

Both cavities were left over one weekend. The resonant frequencies were measured from the peak in the transmission spectra. The sensitivity to temperature seems to be greater for the brazed cavity. This may be attributable to the vacuum sealed feedthroughs. The stability in the frequency difference between the two cavities is 50 kHz/oC.

overtime.png againsttemp.png correlation.png

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Topic revision: r6 - 06 Dec 2013 - FrankieCullinan

 
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