a silicon based mems resistojet for propelling cubesats

13-04-23

Challenge the future

DelftUniversity ofTechnology

A silicon-based MEMS resistojet for propelling cubesatsTittu V. Mathew, B.T.C. Zandbergen, M. Mihailovic, J.F. Creemer, P.M. Sarro.

IAC – 11.C4.3.2.

2Titel van de presentatieDelft University of Technology


Design of a MEMS micro-resistojet

Outline

1. INTRODUCTION 2. DESIGN OF THE THRUSTER

3. FABRICATION USING MEMS TECHNOLOGY

4. TEST RESULTS

5. CONCLUSION

Fabrication using MEMS technology (4/4)



Introduction & thesis objective (5/6)


Introduction (1/2)

T3μPS – cold gas micro-propulsion system developed at TUDelft

Delfi-n3Xt – Student designed 3-unit cubesat to be launched in 2012

4Titel van de presentatie

• High thrust-to-power ratio due to high efficiency• Lower system mass – no power processing units needed• Uncharged plume• Usage with wide variety of propellants

Introduction (2/2) Advantages of resistojet over cold gas and ion thrusters

• Lightweight feature• Small structure -> better thermal

response• Easy integration with other

components on a single PCB• Batch fabrication -> reduction of

manufacturing cost• Widely used in commercial

purposes

Advantages of going for MEMS


Delft University of Technology



Design of the thruster (1/2)

Channel width : 50 μmChannel height : 150 μmFin width : 100 μmNozzle throat width : 10 (/5) μmSingle channel design



Design of the thruster (6/6) Fabrication using MEMS technology (4/4)


Design of the thruster (2/2)





Thrust vs. chamber pressure(Prediction using ideal rocket motor theory)

10 μm nozzle

Chamber pressure [bar]

Th

rust

[m

N]

5 μm nozzle





PECVD SiO2 at both surfaces





Thermal oxidation of silicon at both surfaces

Aluminium deposition and patterning

First DRIE step from wafer backside



Patterning the inlet (2nd DRIE step)

Patterning the channel and nozzle (3rd DRIE step)

Removing SiO2 from the bonding surface; Sealing of the channels by anodic Si-glass wafer bonding




Inlet manifold





SEM image

Silicon

Single channel

Nozzle throat






Silicon

Pyrex

Inlet

Nozzle exit

Packaged device

Needle glues into the inlet manifold

Needle

PCB

Aluminium heater

Nozzle outlet



Test results without propellant heating (1/3)

Test setup



Test results (1/4)




5 μm nozzle

10 μm nozzle

Cold gas test results and discussion (2/4)




Test results (2/4)




Cold gas test results and discussion (4/4)

Throat Reynolds number [-]

Dis

charg

e c

oeff

icie

nt

of

the

nozz

le,

Cd [

-]



5 μm nozzle

10 μm nozzle


Test results (3/4)




Hot gas test results and discussion (4/6)

Heater temperature [C]

Measu

red

pre

ssu

re [

bar]

Test results with propellant heating (4/6)


5 μm nozzle

10 μm nozzle




Test results (4/4)


Hot gas test results and discussion (5/6)

Test results with propellant heating (5/6)

Propellant heating efficiency : < 13%

@ mass flow rate of 1 mg/s


Heater temperature [C]

Ele

ctri

c in

pu

t p

ow

er

[W]



Conclusions & future work (1/2)

Conclusions• Fabricated devices are lightweight (only 162 mg) and dimensions of 25 mm x 5 mm x 1 mm making them very suitable for propelling cubesats • Maximum chamber temperature of 350 ºC achieved with Pel = 2.5 W @ Volt = 10 V

• Specific impulse of 73 sec (without propellant heating) to 104 sec (@ 350 ºC)

• Calculated thrust : 100 μN to 1.2 mN • Effect of low Reynolds number on thruster performance is identified • Technology readiness level of 3 achieved





Thank you for attention

Questions ??

a silicon based mems resistojet for propelling cubesats

Documents

mems fabrication

mems technology test

future fabrication

future test results

future design

thruster fabrication

conclusion fabrication

siliconbased mems resistojet