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Entry  Tue Apr 12 18:42:59 2011, Dmass, tara, DailyProgress, TempCtrl, time constant between can and cavity Slide1.png
    Reply  Tue Apr 12 20:54:36 2011, Dmass, DailyProgress, TempCtrl, time constant between can and cavity 
       Reply  Wed Apr 13 09:18:50 2011, tara, DailyProgress, TempCtrl, time constant between can and cavity 
          Reply  Wed Apr 13 11:25:13 2011, Dmass, DailyProgress, TempCtrl, time constant between can and cavity 
             Reply  Wed Apr 13 11:29:50 2011, tara, DailyProgress, TempCtrl, time constant between can and cavity 
                Reply  Thu Apr 14 10:02:11 2011, tara, DailyProgress, TempCtrl, time constant between can and cavity RCAV_timecon.png
Message ID: 582     Entry time: Thu Apr 14 10:02:11 2011     In reply to: 581
Author: tara 
Type: DailyProgress 
Category: TempCtrl 
Subject: time constant between can and cavity 

Result from a step function test.

          At ~1.5 h, I changed the temperature setpoint from 33.5 to 34.5 C, so the voltage supply to the heater rose up. It reached at 1.7 V and constant because the perl script limited the voltage at that value for preventing any mishap.  The can reached the equilibrium first, in ~ 5.5 hrs after the setpoint was changed. Then the cavity's temperature reached the equilibrium, ~ 3 hrs later. The stack temperature had not reached equilibrium yet.

         Heat transfer mechanism that heats up the cavity seems unlikely to be conduction from can-> stack -> suspension-> cavity. If that were the case, the stack would reach equilibrium before the cavity.

 

RCAV_timecon.png

 I'm repeating the experiment, but this time I turn off the thermal PID feedback of the can temperature, and make a step down in the heater voltage supply, and keep the laser locked to the cavity so that we can read the continuous value from SLOWDC.

 

*I'm sure I made this entry last night. Where did it go?

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