1. PACS IHDR, Garching 12/13 Nov 2003 Chopper R. Hofferbert D. Lemke, U. Grözinger, O. Krause, A. Böhm, A. Bohm (Hardware) R. Vavrek, U. Klaas (ICC) J. Katzer, M. Salvasohn (ZEISS) Max-Planck-Institut für Astronomie, Heidelberg

2. PACS IHDR, Garching 12/13 Nov 2003 2Chopper Specifications - Requirements Chopper characteristics –Cryogenic tilting mirror –Two modes: observation/calibration –Fast square wave modulation schemes –Low power dissipation –High position accuracy

3. PACS IHDR, Garching 12/13 Nov 2003 3Chopper Design Overview top view bottom view

4. PACS IHDR, Garching 12/13 Nov 2003 4Chopper Three independent and fully functional models available (DM, LM, QM) Similarity partly allowed parallel testing to save time and money in the AIV program QM main characteristics –Pre-qualified parts (pigtail, EEE parts, etc.) –Black coating on housing and straylight baffle “Released to the public” –DM 3 times at CSL, once at KT, also in JWST MIRI Phase A study –LM presented at Paris Air Show, also during DLR visit at MPIA –QM officially delivered to PI on June 27 th 2003 Hardware Overview QM DM LM

5. PACS IHDR, Garching 12/13 Nov 2003 5Chopper Qualification Model (QM): –EMC test –Cold 3-axis vibration, 77K, 25g sine, 8g rms random –Cold performance, 4K –Bake-out, 3 days, 80°C Qualification Programme Overview Development Model (DM): –Qualification of components –AIV experience, handling –Interface check with PACS and warm electronics Lifetime Model (LM): –630Mio lifetime cycles –15 thermal cycles (300K - 4K - 300K) vibration performance lifetime integration + inspection

6. PACS IHDR, Garching 12/13 Nov 2003 6Chopper Non-Conformances Status for Oct. 6 th 2003 Telecon! Now!!

7. PACS IHDR, Garching 12/13 Nov 2003 7Chopper QM Acceptance Data Package – IHDR Documents More than 230 individual documents All required management + PA/QA plans Complete chain of test reports systematically structured by chopper models One summarizing NCR list Reviewed CD delivered to PI Entered IHDR package to ESA

8. PACS IHDR, Garching 12/13 Nov 2003 8Chopper Remaining Testmatrix Test variations –Thermal cycling with LM (similar to QM) –Additional test of redundant/failure modes (1..3 coils) –“Fail save position” no longer on requirements list –Bake-out added

9. PACS IHDR, Garching 12/13 Nov 2003 9Chopper FM / FS Verification Flowchart 300K 77K 4K

10. PACS IHDR, Garching 12/13 Nov 2003 10Chopper Schedule today * PI‘s official release awaited *

11. PACS IHDR, Garching 12/13 Nov 2003 11Chopper Test phase (ILT, PV)PCD procedures Subsystem checkout0.7.5 Verify function of PACS chopper 0.7.6 Performance test of chopper and synchronous operation with detectors Functional testsTBD Optimization of PID control loop parameters for plateau stabilization (TBW) 2.3.2 Duty cycle of chopper waveforms 2.3.3 Optimal positioning of chopper on internal calibration sources Spatial performance2.3.1 Angular calibration of chopper (coarse calibration on instrument level) 3.1.2 Relation between chopper position and angular displacement on the sky (fine calibration on full system level) AOT Try-out5.1.1 Optimized observing strategy for photometry of small sources (on-array chopping) ICC – Calibration Requirements

12. PACS IHDR, Garching 12/13 Nov 2003 12Chopper Double stars OGSE black body & hole mask for point source(s) OGSE BB, xy(z) stage & hole mask ICC – Calibration Sequence

13. PACS IHDR, Garching 12/13 Nov 2003 13Chopper set chop_def 0 set chop_pos_max 2 set step 0.05 set reproc 2 # Conversion from degrees (max/min +/- 13.89 deg) to setpoint (32 bit signed integer) set chop_max [expr round(2358. * $chop_pos_max)] set chop_min [expr $chop_max * -1] set chop_incr [expr round(2358. * $step)] set loop [expr (round($chop_pos_max / $step) * 2) + 1] set chop_throw 0.0 # DMC-MOVE-CHOPPER-ABS TCsend PC123420 [list PP079420 $chop_def] WaitTime 500 for {set z 1} {$z<$reproc} {incr z} { for {set x 1} {$x<$loop} {incr x} { if {$x/2 == $x/2.} {set y 1} else {set y -1} set chop_throw [expr round($chop_throw+($chop_incr*$x*$y))] # DMC-MOVE-CHOPPER-ABS TCsend PC123420 [list PP079420 $chop_throw] WaitTime 500 } } # DMC-MOVE-CHOPPER-ABS TCsend PC123420 [list PP079420 $chop_def] WaitTime 500 Setpoint value Array index ICC – Commanding and TM Analysis part of the chopper verify function tcl script IA plot of chopper position data from DMC headers

14. PACS IHDR, Garching 12/13 Nov 2003 14Chopper Ongoing Work - Open Points Chopper operation modes and control schemes –Transfer from MPIA/Zeiss breadboards to flight-like warm electronic boxes  Intensification of exchange process with CSL –Definition and limitation of operation modes (observation, calibration, launch, redundancy in failure cases, …)  Intensification of definition process with PI and PACS commanding group Official FM manufacture release

15. PACS IHDR, Garching 12/13 Nov 2003 15Chopper Conclusion Qualification program completed on subunit level –no critical throwbacks –Chopper QM + complete acceptance data package delivered to PI –Support on instrument level available and already used –Industrial PA/QA accompanied all development stages –Extensive transfer phase between QM and FM, no major changes Flight program started –Manufacture on the way –Components procurement completed, selection process + pre- qualification running –Subunit AIV planning presently starting (preparation of ground support equipment, overall test plan, detailed procedures) –FM + FS development in parallel (time + cost saving reasons) –Delivery to PI: June 2004