Plato at ASI Tues 05/May/09Dave Walton Plato meeting Rome Tues 5/May/09 Focal Plane Dave Walton UCL/MSSL, + Leicester University Miguel Mas INTA/CAB + LIDAX (Javier Serrano mechanical + thermal) Recent changes, current issues etc. in red

Plato at ASI Tues 05/May/09Dave Walton FPA: location in relation to telescope

Plato at ASI Tues 05/May/09Dave Walton TOU FLANGE SUPPORT BIPODS (x4) FEE Box COLD PLATE CCDS Assembly PLATO – FPA & FEE Design Concept ( ) 80mm OPTICAL BENCH MLI

Plato at ASI Tues 05/May/09Dave Walton PLATO – FPA & FEE Design Concept ( ) SUPPORT BIPOD THERMAL STRAPS (x4) Flex Cable CCDs Support Plate CCD CCD Base

Plato at ASI Tues 05/May/09Dave Walton SPACE TOU HEATER 158K-168K 0.49 W-0.88W COLD PLATE FLEXCABLES (4mW/K) 2.51W-2.12 W FEE FPA 159K-169K 249K-308K 243K-303K OB MLI 158K-168K PLATO – FPA & FEE Thermal Performance ( ) 1.5W-1.9 W 1.0W 3.0W Temperature (pink): assumption Temperature (blue): result COLD-HOT CASES 243K-303K

Plato at ASI Tues 05/May/09Dave Walton 1. Concept design based on FEE in an independent box on Cold Plate and FPA attached to TOU is shown 2. Two different thermal cases (cold & hot) have been analyzed 3. Thermal performance for both cases is according to requirements, but assumptions must be confirmed by system level 4. Spatial gradients across CCDs are about 0.1K 5. Temporal gradients on CCD shall mainly depend on TOU temporal gradient 6. If TOU temporal gradient is >1K/40 days (FPA Requirement), heaters on FPA will be required to comply with 1K/40 days gradient PLATO – FPA & FEE Thermo-mechanical conclusions ( )

Plato at ASI Tues 05/May/09Dave Walton PLATO FPA Thermo-mechanical Design Mass Budget Mass Budget (per FPA, including FEE & CCDs) ITEMMASS CCDs600 CCD Support Plate110 FEE bracket470 FEE lower cover260 FEE470 Thermal strap88 TOTAL1998 TOTAL with 20% margin2398

Plato at ASI Tues 05/May/09Dave Walton CCD: Using Gaia for prototyping Gaia CCD at MSSL Plato CCD characteristics Flight: 42 telescopes, 4 CCDs per telescope -> 168 flight CCDs. Each CCD 3584x µm pixels. Full-frame (except for 2 bright-source telescopes using same chip but frame transfer). Red-enhanced AR coating. Thin oxide and doping to increase full-well to ~1Me -.

Plato at ASI Tues 05/May/09Dave Walton Normal telescope electrical architecture 8 output ports multiplexed into 2 ADCs

Plato at ASI Tues 05/May/09Dave Walton Normal telescope: Time-multiplexing of CCDs In order to remain close to FEE power budget, may be necessary to unpower CCD output nodes when not active

Plato at ASI Tues 05/May/09Dave Walton Fast telescope electrical architecture Due to high duty cycle, 1 ADC per port required. Similarly, unpowering of CCD output stages not possible Therefore, power consumption significantly higher than normal telescope, so just as well there are only two.

Plato at ASI Tues 05/May/09Dave Walton Normal and fast telescope power calculations * Not using CCD dummy outputs * Normal telescope duty cycle: 4s each 25s Power in mW, per telescope Normal Power- cycled Normal Continuous power BUDGETFast Continuous power BUDGET FPA, 2ndary FEE, 2ndary TOTAL, primary

Plato at ASI Tues 05/May/09Dave Walton CCD Procurement: Delivery rate Potentially 42 telescopes, -> 168 flight CCDs. e2v confirm this is feasible in a 3-phase programme: Phase 1: Development activities – 18 months Phase 2: Evaluation activities and FM preparation – 18 months Phase 3: FM manufacturing – 6 month startup, 18 months delivery (~10 per month) Total duration: 5 years, so needs early planning. ESA have queried delivery rate, based on Gaia rate. Response from e2v: * Agree the device is somewhat larger. However, from Gaia experience, more than half of yield loss was not area-related (e.g. mechanical packaging). * Plato delivery rate higher than Gaia, but not by a huge margin (~10 per month). Can be accommodated: more an issue of planning the resources rather than e2v’s capacity. e2v’s existing capacity 16 per month. * Cyril Vetel (Astrium) very pleased with progress of Gaia CCD procurement. For further clarification, MSSL will set up a meeting with representatives from e2v, PPLC and ESA

Plato at ASI Tues 05/May/09Dave Walton CCD Procurement: Increased full-well / dynamic-range Following discussions with e2v, full-well increased by combination of thin oxide and doping profile. In Dave Morris’s note, he assumed a lower yield for thin oxide devices, and was satisfied that the delivery rate could be achieved. Recent tests by e2v of small area devices showed a similar yield to normal devices.

Plato at ASI Tues 05/May/09Dave Walton CCD Temperature PDD assumed T CCD ~-100 C (173 K). Design/implementation simpler if T CCD ~-70 C (203 K). PPLC now adopts baseline of <-70 C (<203 K). Issues: Dark current: Not a problem at these temperatures (much lower than other noise sources) CTE effects from irradiation-induced traps: the principal reason for -100C in PDD. Being addressed by simulation, comparison with Corot, Integral data.

Plato at ASI Tues 05/May/09Dave Walton Summary/Status FPA/FEE Design, layout, thermal modelling and power consumption calculations are progressing. Thermal modelling for normal telescopes consistent with requirements. Power consumption within PPLC budget for normal telescopes. Higher for fast telescopes, but these have a small impact on total power. Fast telescopes should now be thermally modelled (power numbers now available). Dynamic-range / full-well increased after discussion with e2v. CCD supply rate analysed, considered realistic. OVERALL: No show-stoppers, FPA/FEE considered to be within conservative feasibility.

Plato at ASI Tues 05/May/09Dave Walton Reserve slides

Plato at ASI Tues 05/May/09Dave Walton Alternative layout: To ease mounting to optical bench and cold plate

Plato at ASI Tues 05/May/09Dave Walton PLATO FPA Thermomechanical Design Previous Design from LIDAX MASK SHIM CCDs + CCD SUPPORT PLATE FPA HOUSING FEE + FEE SUPPORT PLATE COVER THERMAL STRAP