The pdf file is uploaded into the wiki.

Gautam and Steve,

We have calibrated the load  cells. The support beams height monitoring is almost ready.

The danger of this measurment that  the beams height changes can put shear and torsional forces on this formed (thin walled) bellow

They are designed for mainly axial motion.

The plan is to limit height change to 0.020" max

0, center oplev at X arm locked

1, check that  jack screws are carrying full loads and set height indicator dials to zero ( meaning: Stacis is bypassed )

2, raise beam height with aux leveling wedge  by 0.010"  on all 3 support point and than raise it an other 0.005"

3, replace levelling wedge with load cell that is centered and shimmed.     Dennis   Coyne pointed out that the Stacis foot has to be loaded at the center of the foot and formed bellow can shear at their limits.

4, lower the support beam by 0.005" ......now full load on the cells

Note: jack screw heights will not be adjusted or  touched.......so the present condition will be recovered

[ Dennis Coyne'  precision answer ]

Differential Height between Isolators

According to a note on the bellows drawing (D990577-x0/A), the design life of the bellows at ± 20 minutes rotational stroke is 10,000 cycles. A 20 minute angular (torsional) rotation of the bellows corresponds to 0.186" differential height change across the 32" span between the chamber support beams (see isolator bracket, D000187-x0/B).

Another consideration regarding the bellows is the lateral shear stress introduced by the vertical translation. The notes on the bellows drawing do not give lateral shear limits. According to MDC's web page for formed bellows in this size range the lateral deflection limit is approximately 10% of the "live length" (aka "active length", or length of the convoluted section). According to the bellows drawing the active length is 3.5", so the maximum allowable lateral deflection should be ~0.35".

Of course when imposing a differential height change both torsional and lateral shear is introduced at the same time. Considering both limits together, the maximum differential height change should be < 0.12".

One final consideration is the initial stress to which the bellows are currently subjected due to a non-centered support beam from tolerances in the assembly and initial installation. Although we do not know this de-centering, we can guess that it may be of the order of ~ 0.04". So the final allowable differential height adjustment from the perspective of bellows stress is < 0.08".   Steve:  accumulated initial stress is unknown.  We used to adjust the original jack screws for IFO aligment in the early days of ~1999. This kind of adjustment was stopped when we realized how dangereous it can be. The fact is that there must be unknown amount of accumulated initial stress. This is my main worry but I'm confident that 0.020" change is safe.

So, with regard to bellows stress alone, your procedure to limit the differential height change to <0.020" is safe and prudent.

However, a more stringent consideration is the coplanarity requirement (TMC Stacis 2000 User's Manual, Doc. No. SERV 04-98-1, May 6, 1991, Rev. 1), section 2, "Installation",which stipulates < 0.010"/ft, or < 0.027" differential height across the 32" span between the chamber support beams. Again, your procedure to limit the differential height change to < 0.02" is safe.

Centered Load on the STACIS Isolators

According to the TMC Stacis 2000 User's Manual (Document No. SERV 04-98-1, May 6, 1991, Rev. 1), section 2, "Installation", typical installations (Figure 2-3) are with one payload interface plate which spans the entire set of 3 or 4 STACIS actuators. Our payload interface is unique.

Section 2.3.1, "Installation Steps": "5. Verify that the top of each isolator is fully under the payload/interface plate; this is essential to ensure proper support and leveling. The payload or interface plate should cover the entire top surface of the Isolator or the entire contact area of the optional jack."

section 2.3.2, "Payload/STACIS Interface": "... or if the supporting points do not completely cover the top surface of each Isolator, an interface plate will be needed."

The sketch in Figure 2-2 indicates an optional leveling jack which appears to have a larger contact surface area than the jacks currently installed in the 40m Lab. Of course this is just a non-dimensioned sketch. Are the jacks used by the 40m Lab provided by TMC, or did we (LIGO) choose them? I beleive Larry Jones purchased them.

A load centering requirement is not explicitly stated, but I think the stipulation to cover the entire top surface of each actuator is not so much to reduce the contact stress but to entire a centered load so that the PZT stack does not have a reaction moment.

From one of the photos in the 40m elog entry (specifically jack_screw.jpg), it appears that at least some isolators have the load off center. You should use this measurement of the load as an opportunity to re-center the loads on the Isolators.

In section 2.3.3, "Earthquake Restraints" restraints are suggested to prevent damage from earth tremors. Does the 40m Lab have EQ restraints? Yes, it has

Screw Jack Location

I could not tell where all of the screw jacks will be placed from the sketch included in the 40m elog entry which outlines the proposed procedure.

Load Cell Locations

The sketch indicates that the load cells will be placed on the center of the tops of the Isolators. This is good. However while discussing the procedure with Gautam he said that he was under the impression that the load cell woudl be placed next to the leveling jack, off-center. This condition may damage the PZT stack. I suggest that the leveling jack be removed and replaced (temporarily) with the load cell, plus any spacer required to make up the height difference. Yes

If you have any further question, just let me know.

    Dennis

Dennis Coyne
Chief Engineer, LIGO Laboratory
California Institute of Technology
MC 100-36, 1200 E. California Blvd.

20180508 4:49am Cabazon earth quake 4.5M at 79 miles away.  ETMX is in load cell measurment condition.

Pooja and Keirthana received 40m specific basic safety training.

The final set-up of stack measurment with 3 load cells and 4 leveling wedge mounts as Atm 1

Sensor voltages BEFORE and AFTER this attempt.

Chris replaced some air condition filters and ordered some replacement filter today.

Koji's collection of Yend components put away. I cleaned up the  Xend bench today.

Loadcells, leveling wedge mounts  and related items placed under flowbench cabinet next to Guralp staff.

We have 6 of these boards now in cabinet E7

The cabeling was cleaned up a little bit yesterday morning. The upper back side is still massy.

Oplev sums of 240 days.

You should wipe off the table cover before you take it off next time.

It is important to turn up the PSL encloure HEPA Variac voltage if you are working in there. It takes less than 10 minutes to reach lab condition.

Lab air count normal. It is not logged. I have a notebook of particle count on the SP table next to the Met One counter.

We may lost the UL magnet or LED

4  std cataloge item fused silica  BS1-1064-95-2025-45UNP 

ordered today. They will arrive no later than July 13, 2018

The fardest I can go back on channel C1: Vac_N2pres is  320 days

C1:Vac-CC1_Hornet Presuure gauge started logging Feb. 23, 2018

Did you update the " low N2 message"  email addresses?

Shruti and Sandrine received 40m specific basic safety training this morning.

This bad connection is coming back

We are getting ready to vent.

Steve and Aaron,

6 hrs vent is reaching equlibrium to room air. It took 3 and a half instrument grade air cilynders [ AI UZ300 as labelled ] at 10 psi pressure. Average vent speed ~ 2 Torr/min

Valve configuration: IFO at atm and RGA is pumped through VM2 by TP1 maglev.

Precondition:  4 days at atm.   Atm5

HEPA tent used during the vent at ETMY  It reduced partical count 10 fold of 0.5 and 0.3 micron particals. Atm6

New items in vacuum:  Clean manual gate valve [Cetec made] from John Worden with 6" id....as it came from Hanford... [ Throttle able gate valve- TGV ] Atm3

                                 ( note: we have 3 more identical in the lab. The original intention was to use them for purging gates )

                                  Optiform Au plated reflector , Induceramics heating elements, similar as existing Cooner cables and related lenses, hardwear. see 14078

                                  OMC related item : none......... 14,110

The pumpdown is at 510 mTorr with RP1 & RP3 still pumping. Koji will shut it down the roughing later tonight. Tomorrow morning I will start the pumping by switching over to TP1 maglev.

Thanks for Koji and Gautam'  help of the installation of the manual gate valve. Atm4  This will allow us to control the load on our Varian foreline D70 turbo TP3

The manual gate valve scan was clean. Atm1     TP1 was pumping on it overnight.

                                                Pumpdown continued to hand over the pumping to TP1 maglev turbo

V1 was opened at P1 400 mTorr  with manual gate at 3/4 turn open position as Magev at 560 Hz rotation.

Two aux fans on to hold tubo temps TP1 & TP3 . Atm3

This is the first time we pumping down from atm with ONE small "beer can" turbo  and throttled gate valve to control load on small turbo forepump

The 70 l/s turbo is operating at 50k RPM, 0.7 A and 31 C,  pumping speed  ~ 44 mTorr/h at 200-400 mTorr range with aux drypump in the foreline of TP3

Watching foreline pressures and current one can keep opening gate valve little by little the so the load is optimized. It is working but not fast.

Let's keep small turbo at 0.8 Amp and 32 C max at this pumpdown. 

IFO P1 6e-4 Torr,  manual gate valve is fully open

The annuloses will be pumped down tomorrow.

Valve configuration: vacuum normal, RGA and annuloses are not pumped

Cold cathode gauge just turned on.

Roughing down the annuloses required closing V1 for 13 minutes

IFO is 2.2e-5 Torr

New optical quality BK-7 windows in 2001 [4 substrates ] AR coated R<0.75 % for 630-1064nm " Azury BLue" broadband : TRX, TRY, ITMY-Oplev &  ITMX-Oplev viewports.

The BS-Oplev and PRM-Oplev 10" CF with 5.38" diameter view was coated the same way. The window here is Corning 7056 Borosilicate

5 more BK-7 substrates were coated R <0.1% of 1064 nm "Golden Orange" Their location: IMC-IN, IFO-REF and OMC   The next vent we have to confirm optical quality window locations.

All other conflat flange viewports are 7056 Kovar sealed .

Technical notes of 2001 40m upgrade can be seen at LIGO-T010115- 00- R  ....page 14

Yesterday I inspected this BS oplev viewport. The heavy connector tube was shorting to table so It was moved back towards the chamber. The connection is air tight with kapton tape temporarly.

 The beam paths are well centered. The viewport is dusty on the inside.

The motivation was to improve the oplev noise.

I 've just found this time capsule note from Nov. 26, 2000 by Kip Thorne:  LIGO will discover gravitational waves by Dec.31, 2007

Here is an other big one

Basic Pump Throughput Concepts

What is Pump Throughput?

The manufacturer of a vacuum pump supplies a chart for each pump showing pumping speed (volume in unit time) vs pressure. The example, for a fictitious pump, shows the pumping speed is substantially constant over a large pressure range.

By multiplying pumping speed by pressure at which that pumping speed occurs, we get a measure called pump throughput. We can tabulate those results, as shown in the table below, or plot them as a graph of pressure vs pump throughput. As is clear from the chart,  pump throughput (which might also be called mass flow) decreases proportionally with PRESSURE, at least over the pressure range where pumping speed is constant.

The roughing pump speed actually will reach 0 l/s  at it's ultimate pressure performance.

Our roughing pump  pumping speed will slowly drop  as chamber pressure drops. Below 10 Torr this decrease is accelerated and bottoms out. This where the Root pump can help. See NASA evaluation of dry rough pumps...What is a root pump 

We have been operating succsessfully with a narrow margin. The danger is that the Maglev forline peaks at 4 Torr. This puts load on the small turbo TP2, TP3 &  large TP1

The temperature of these TP2 & 3  70 l/s drag turbos go up to 38 C and their  rotation speed slow to 45K rpm from 50K rpm because of the large volume 33,000 liters

Either high temp or low rotation speed of drag turbo or long time of overloading  can shut down the small turbo pumps......meaning: stop pumping, wait till they cool down

The manual gate valve installed helped to lower peak temp to 32C It just took too long.

We have been running with 2 external fans [one on TP1 & one on TP3]  for cooling and one aux drypump to help lowering the foreline pressure of TP2 & 3

The vacuum control upgrade should include adding root pump into the zero pumping speed range.

Atm1,   Pump speed chart:   TP1  turbo -red, root pump -blue and mechanical pump green. Note green color here representing an oily rotory pump. Our small drypumps [SH-100] typically run above 100 mTorr

                                           They are the forepump of TP2 & 3     Our pumpdown procedure: Oily Leybold rotory pumps ( with safety orifice 350 mT to atm ) rough to 500 mTorr

                                                                                                 Here we switch over to TP2 & 3 running at 50k RPM with drypumps SH-100 plus Aux Triscroll

                                                                                                 TP1- Maglev rotating full speed when V1 is opened at full volume at 500 mTorr 

                         History: the original design of the early 1990s had no dry scroll pumps. Oil free dry scrools replaced the oily forepumps of TP2 & TP3 in ~2002  at the cost of degrading the forline pressure somewhat.

                                     We had 2 temperature related Maglev failers in 2005 Aug 8 and 2006 April 5  Osaka advised us to use AUX fan to cool TP1  This helped. 

Atm2,   Wanted Root pump - Leybold EcoDry 65 plus  

Atm3,   Typical 8 hrs pumpdown from 2007 with TP2 & 3 

Atm4,   Last pumpdown zoomed in from 400 mT to 1mT with throttled gate  valve took 9 hrs  The foreline pressure of TP1 peaked at 290 mT, TP3 temperature peaked at 32C

            This technic is workable, but 9 hrs is too long.

Atm5,   The lowest pressure achived in  the 40m Vacuum Envelope 5e-7 Torr with pumps Maglev  ~300 l/s,  Cryo 1500 l/s  and 3 ion pumps of 500 l/s      [ in April 2002 at pumpdown 53 day 7 ] with annuloses at ~ 10 mTorr

Atm6,  Osaka TG390MCAB Throughput with screen ~300 L/s at 12 cfm backing pump

6.2M Bandon, OR did not trip any sus

Glitch, small amplitude, 350 counts  &  no trip.

The second big glich trips ETMX sus. There were small earth quakes around the glitches. It's damping recovered.

Small earth quakes and suspensions. Which one is the most free and most sensitive: ITMX

The rat is cut by mechanical trap and it was removed from ITMX south west location.

A nagy kover patkanyt a fogo elkapta es megolte.

All suspension tripped. Their damping restored. The MC is locked.

ITMX-UL & side magnets are stuck.

TP-1 Osaka maglev controller  [  model TCO10M,  ser V3F04J07 ]  needs maintenance. Alarm led  on indicating  that we need Lv2 service.

The turbo and the controller are in good working order.

*****************************

Hi Steve,

Our maintenance level 2 service price is $...... It consists of a complete disassembly of the controller for internal cleaning of all ICB’s, replacement of all main board capacitors, replacement of all internal cooling units, ROM battery replacement, re-assembly, and mandatory final testing to make sure it meets our factory specifications. Turnaround time is approximately 3 weeks.

  RMA 5686 has been assigned to Caltech’s returning TC010M controller. Attached please find our RMA forms. Complete and return them to us via email, along with your PO, prior to shipping the cont

Best regards,

Pedro Gutierrez

Osaka Vacuum USA, Inc.

510-770-0100 x 109

*************************************************

our TP-1 TG390MCAB is 9 years old. What is the life expectancy of this turbo?

                        The Osaka maglev turbopumps are designed with a 100,000 hours(or ~ 10 operating years) life span but as you know most of our end-users are

                        running their Osaka maglev turbopumps in excess of 10+, 15+ years continuously.     The 100,000 hours design value is based upon the AL material being rotated at

                        the given speed.   But the design fudge factor have somehow elongated the practical life span.  

We should have the cost of new maglev & controller in next year budget. I  put the quote into the wiki.

Electrician is coming to fix one of the fluorenent light fixture holder in the east arm tomorrow morning at 8am. He will be out by 9am.

The job did not get done. There was no scaffolding or ladder to reach troubled areas.

Yuki Miyazaki received 40m specific basic safety training.

M3.4 Colton shake did not trip sus.

Precondition: c1vac1 & c1vac2 all LED warning lights green [ atm3 ], the only error message is in the gauge readings NO COMM, dataviewer will plot zero [ atm1 ], valves are operational

When our vacuum gauges read " NO COMM " than our INTERLOCKS  do  NOT communicate either.

So V1 gate valve and PSL output shutter can not be triggered to close if the the IFO pressure goes up.                        

   [ only CC1_HORNET_PRESSURE reading is working in this condition because it goes to a different compuer ]