plato at asi tues 05/may/09dave walton plato meeting rome tues 5/may/09 focal plane dave walton...

Plato at ASI Tues 05/May/09 Dave 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


FPA: location in relation to telescope


TOU FLANGE

SUPPORT BIPODS (x4)

FEE Box

COLD PLATE

CCDS Assembly

PLATO – FPA & FEE Design Concept (2009-04-30)PLATO – FPA & FEE Design Concept (2009-04-30)

80mm

OPTICAL BENCH

MLI


PLATO – FPA & FEE Design Concept (2009-04-30)PLATO – FPA & FEE Design Concept (2009-04-30)

SUPPORT BIPOD

THERMAL STRAPS (x4)

Flex Cable

CCDs Support Plate

CCDCCD Base


SPACE

TOUHEATER

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 OB

MLI

158K-168K

PLATO – FPA & FEEThermal Performance (2009-04-30)PLATO – FPA & FEEThermal Performance (2009-04-30)

1.5W-1.9 W

1.0W

3.0W Temperature (pink): assumption

Temperature (blue): result

COLD-HOT CASES

243K-303K


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 (2009-05-05)PLATO – FPA & FEE Thermo-mechanical conclusions (2009-05-05)


PLATO FPA Thermo-mechanical Design Mass BudgetPLATO FPA Thermo-mechanical Design Mass Budget

Mass Budget (per FPA, including FEE & CCDs)

ITEM MASS

CCDs 600

CCD Support Plate 110

FEE bracket 470

FEE lower cover 260

FEE 470

Thermal strap 88

TOTAL 1998

TOTAL with 20% margin 2398


CCD: Using Gaia for prototyping

Gaia CCD at MSSL

Plato CCD characteristics

• Flight: 42 telescopes, 4 CCDs per telescope -> 168 flight CCDs.

•Each CCD 3584x3584 18µm pixels.Full-frame (except for 2 bright-source telescopesusing same chip butframe transfer).Red-enhanced AR coating.

• Thin oxide and doping to increase full-well to ~1Me-.


Normal telescope electrical architecture

• 8 output ports multiplexed into 2 ADCs


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


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.


Normal and fast telescope power calculations

* Not using CCD dummy outputs * Normal telescope duty cycle: 4s each 25s

Power in mW, per telescope

NormalPower-cycled

NormalContinuous power

BUDGET FastContinuous power

BUDGET

FPA, 2ndary

314 717 1000 2925 2500

FEE, 2ndary

3530 5217 3000 11203 7000

TOTAL, primary

5491 8478 5700 20182 13600


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 monthsPhase 2: Evaluation activities and FM preparation – 18 monthsPhase 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


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.


CCD Temperature

• PDD assumed TCCD ~-100 C (173 K).• Design/implementation simpler if TCCD ~-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.


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.


Reserve slides


Alternative layout: To ease mounting to optical bench and cold plate


PLATO FPA Thermomechanical Design Previous Design from LIDAXPLATO FPA Thermomechanical Design Previous Design from LIDAX

MASK

SHIM

CCDs + CCD SUPPORT PLATE

FPA HOUSING

FEE + FEE SUPPORT PLATE

COVER

THERMAL STRAP

plato at asi tues 05/may/09dave walton plato meeting rome tues 5/may/09 focal plane dave walton...

Documents

05may09dave walton fpa

05may09dave walton ccd

w fee fpa

fee power budget

telescope normal power

red slide

active slide

margin2398 slide