Had system in //return cooling overnight with small flow to keep power 
leads cool. Switched to series mode about 30 minutes ago. Building LHe 
level.

Powerleads appear stable.

Mu2 pressure was just about at trip point due to trapped volume of helium 
warming. So opened up warm returns to bleed off pressure and prevent it 
from rising.

TIC121 was down to 27K
warm return valves were wide open
opened supply valves CV143 and CV146.
TIC121 went up to about 37K
Mu1 return temperature went down to about same temp as TIC121 so set Mu1 to 
cold return. Open CV145 then close CV151. Mu2 return was still > TIC121 so 
kept it in warm return mode. Adjust turbines as required.
After about 20 minutes Mu2 return temp dropped down to about equal to Mu1 
return temp of about 38K. Then set Mu2 to cold return. Open CV147 then 
close CV143. TIC 121 drops to 30 K. Even though Mu1 and Mu2 return temps 
greater than TIC121 I will keep it in //cold return mode to see if the core 
solenoid temperatures will start to fall. To maximize the use of the 
cooling from T2 outlet temperature CV155 is tweaked open to its maximum 
stable opening. This helps cool the lower heat exchangers. If this works 
then cr_c1 and cr_c12 should start to tick downwards. If they keep rising 
then have to switch back to //warm return.

cr_c1 and cr_12 are both at about 45K and heading slowly down, so the 
gamble of going to // cold return worked. Maximum opening of CV155 is 
limited by CV204 goes fully closed and suction pressure begins to rise 
above set point. Adjust cv155 to keep cv204 just at the closed point. Keep 
tweaking cv155 and turbine speeds as things get cooler.

Even though cr_c1 and cr_c12 have begun to tick down, cr_c7 and cr_c6 are 
actually ticking up. This is probably a wave of warming propagating through 
the solenoid. As long as the two inlets are falling in temperature then 
things are going in the right direction. Once the warm wave travels through 
the outlets will begin to cool as well.

Power leads have flatlined but still building LHe level.

After restarting flow to the solenoid yesterday in // cold return mode 
TIC121 just refused to go lower than about 29K even when we closed CV155 
all the way. Tried various things, switching to // warm return, changing 
opening of CV155, setting TIC121 to auto, even tapping TIC121. Finally 
tried reducing flow to solenoid by reducing // warm return valves to about 
70% open to see if possible to cool just refrigerator a bit.

TIC121 temp fell a bit and then inlet temperatures to solenoid began to 
fall and solenoid slowly began to cool even though the mass flow to the 
solenoid was reduced. Guess is that with solenoid homogeneusly at about 30K 
there was not much resistance to flow so turbine massflow was starved just 
enough to stall further cooling.

After temps were on a good downward trend Doug switched to //cold return. 
At about 16:00 yesterday I reduced CV155 to about 70% and waited a bit to 
confirm that temps were falling and then left the system to cool until 
later that evening.

About 21:00 last night the solenoid temps had not changed much, pretty well 
flat lined. I guess my reducing CV155 stalled the cooling. Called Don 
Arseneau and asked him to increase CV155 to about 80% open. Temps slowly 
began to fall. Asked Don to look at graph of temps later in the night and 
if they fall down to a flat line to then reduce CV155 a bit to get the 
temps trending further down.

This morning CR_C1_ENT has fallen to a slightly upward trending flat line 
of about 12.7 K. Probably ready for switching to series mode by whoever 
gets to the system first this morning.

Power lead temps were drifting up, tried to tweak TIC121 and HIC141 to 
unstall powerlead flow. Got quench. Restarted series flow, building LHe 
level.

Powerleads seem stable.

Return flow temps from solenoid about 40K, TIC121 at about 40K so switching 
to //cold return.
Starting with slightly reduced flow through cold returns, CV145 and CV147 
at about 65% open.

Temps of flow returning from solenoid flat lined at about 10K.
Gradually closed CV155.
Then switched to series cooling.

System in good // warm return mode, temps coming down nicely. BCP2 cryopump 
does not look too healthy, temperature is just over 20K, very close to low 
set point.

TIC121 down to 120K, Mu1 return temp at 164K, Mu2 return at 273K, T1 inlet 
temp at 208K. Cooling looks good for overnight.

Main compressor tripped, refrigerator shutdown. Checked with experimentors 
and main control room, no indications of power bump etc.

Restarted compressor, // warm then // cold return. One of the MV5x valves 
frozen open, had to de-power valve  a couple of times to get it to seal.

Switched to series mode about 6 hours ago. Cooling continued including 
power leads until LHe level at about 50% and powerleads appeared stable.

02:30 this morning got page from operations.
Looked at system online, appears that there was a powerlead overtemp
that caused the quench. Compressor still running. After arriving to 
work set system to // warm return mode to cool down transferlines. Lhe 
level starts to boil away. Switch to // cold return mode. Discovered that 
seem to get better cooldown rate by not opening supply valves to solenoid 
fully. // cold return valves are fully open but both CV143 and CV146 are 
only open to 0.55 giving mu1 and mu2 inlet pressures of 2 barA. Getting 
good cool down rates and even building LHe level.

04:25 C1 down to 8K, C12 at 7.5K, C6 at 7.5K, 6KS_M at 10.5K

Leaving system cooling in // cold return mode, cooldown rates still good. 
Had flow on to powerleads since re-starting cooling flow to solenoid.
Either I (when I return to work later this morning) or Doug will do the 
switch to series mode.

Powerlead temperatures have bottomed out, energizing solenoid to 300 
amps, ramp rate 60.

At 10:30 PM Saturday, Donald Arseneau sees power leads at
25K, having gone up for the previous 10 hours.  (I didn't
see it earlier because striptool wasn't scrolling).  Cycled
valve 142.
--  Donald Arseneau