Magnetometer Design

Minutes

Meeting
Tuesday, June 22
Feasablilty
  • PPM
    • No way
    • No good resorces
    • No usable liquid at 1 K
  • Fluxgate
    • Cubical 3D MAG
      • Doable
      • takes 200 mW
      • little larger than a penny square
  • Hall Effect
    • Doable
    • .1 uV/.01G
    • making plate thinner would reduce current needed
  • AMR
    • Doable
    • in tesla range
    • PNI
      • much smaller than a penny
      • not 3D
      • 1500uW/Vector
      • need to look into patents
      • Less than 500 uA
      • No way to get it in the range of a few K
  • GMR
    • No way
    • will not measure fields that low

Next Meeting: Thursday, June 24 10-11:30am

Assignments:

  • Working concepts
    • Equations
    • Sketches
    • Materials
    • Cost
  • Fluxgate
    • Andrew
    • Kat
  • Hall Effect
    • Steve
    • Crayton
  • AMR
    • Kristen
    • Chris

Telecon Meeting
Thursday, June 17

  • Things to discuss with Simon
    • Hall might work with gold leaf
    • PPM will not work due to H phase diagram
    • AMR
      • Magneto-Inductor (MI) is cooler and might not drift
      • Temperature drift. no worse than Hall
      • Sensing distance?
    • Fluxgate
      • Seems like a safe bet
    • Hall
    • Could we get some 40 Gauge wire?
  • Telecon
    • Power should be on the order of one MICROwatt for entire package
      Can go up to 20 or more microwatts, esp if each axis is independent, but they can't run it for very long
      We can test at Goddard
      We'll get back to Simon about wire or we can talk to John directly
      California Fine Wire is best for fine wire but takes three months to get
      SuperCon is best for superconducting, but takes three months to get
      Do we want high or low thermal conductivity?
  • Next Meeting
    • Choose 2 design concepts

Meeting & Lab
Tuesday, June 15
  • Talked with Steve Holt about feasibility
    • Do not completely rule out Hall Effect Sensors
    • PPM may have problem with liquid at <1K temps
  • Lab
    • Made Fluxgate coils
    • Attempted to make nulling circuit
    • Used function generators
    • Could not get a reading off the occiliscope
  • Next Meeting Agenda
    • Narrow down options
    • List of questions/clarifications for telecon
    • Mini presentation
Assignments:
  • Kristen
    • AMR & GMR
    • Hall Effect sensors
  • Andrew
    • Fluxgates
  • Chris
    • AMR& GMR
    • PPM
  • Michael
    • PPM
    • Mu Metal
  • Kat
    • Website
    • AMR& GMR
    • Permalloy

 

Feasibility Meeting
Friday, June 11

  • Webstie manager: Kat
  • Alternating Gradient
    • Can operate at low temps
    • Part of it uses Hall effect and coils
    • Very sensitive
    • Take up entire rooms
    • Not usable
  • Vector/Scalar Helium & Laser pumped MAG
    • Previously used in cryo space apps
    • Still being researched
    • Not usable
  • DC Squid
    • Far too sensitive
    • Not usable
  • Anisotropic Magnetoresistive MAG (AMR)
    • Very sensitive
    • Small
    • Consumes less power than fluxgate
    • Possibly usable
  • Proton Precession MAG (PPM)
    • Uses fluid
    • Possibly usable
  • Hall Effect
    • Uses semiconductors, which do not work at low temps
    • Regular conductors need obscene current
    • Need to look into superconductors
    • Possibly usable
  • Fluxgate
    • Already used at liquid He temps
    • Commercially available at 50 mW
    • Range - 0 to 0.2mT
    • Looks usable ^_^
  • Timeline
    • Wednesday, June 16 - Telecon
    • Friday June 18 - Choose two designs
    • Friday June 25 - Finish Designs
    • Friday July 9 - Finish Fabrication
    • Wednesday July 14 - Finish Testing
    • Friday July 16 - Send Prototypes

Organizational Meeting
Wednesday, June 9
  • Project Leader: Kristen
  • From Telecon
    • Hall Probes do not work below 4 K
    • No on currently makes low temp fluxgates
    • Need to see if fluxgates can work at low temps
    • Goddard can send superconducting wire
  • Specifications for each MAG
    • Size
    • Power
    • Sensitivity
    • Tesla Range
    • Ease of Calibration
    • Operating temperatures
Assignments:
  • Kristen
    • Magnetoresistors/Resonant MAGs
    • Alternating Gradient MAGs
    • Vector Scalar Helium MAGs
  • Steve
    • Hall Effect Sensors
    • Super conducting HES
  • Andrew
    • Fluxgates
  • Chris
    • PPM
  • Michael
    • DC SQUIDs
  • Kat
    • Optical & laser pumped vector MAGs

 

Teleconference
Tuesday, June 8

  • Talked to Simon
  • Things we want in the Magnetometer
    • Small size
    • Cryogenic
    • Low power
    • Low heat output
    • High Hall voltage
  • Questions & Answers
    • Where in the dewar is the magnetometer used?
      • Inside detector box
      • Sitting on top of cold plate
    • Is there a magnetometer being used now?
      • No
      • Need MAG for absolute measurements inside box
    • What is the temperature range?
      • Less than 1K
    • How much space is avaliable?
      • Less than 1 inch diameter
    • Will it be stationay?
      • Yes, Mounted.
    • What Tesla range is needed?
      • Below 0.1 Gauss
      • More sensitive the better
    • Will the magnetic field be constant or dynamic?
      • Unsure
      • That's what this MAG is for
    • What is the allowable heat dissapation and power draw?
      • Less than 1 mW
    • Is there a timeline for this project?
      • Not really
      • Before the end of summer would be nice
    • Are Hall Effect sensors and option?
      • Hall Effect Sensors cannot work below 4K
    • What are calibration requriements?
      • Should be able to be recalibrated
      • Maybe moved to different locations
    • What are the most important aspects?
      • Size
      • Heat disspation

Organizational Meeting
Monday, June 7

  • Goal: Creat a 3D cryogenic magnetometer that uses low power
  • Types of MAGs
    • Hall Effect Sensors
    • Fluxgate MAGs
    • Moving Coils
    • Other MAGs
  • Factors
    • Heat Disspation
    • Power usage
    • Dimentiality
    • Size
    • Materials
    • Relative costs
  • Questions
    • Position in ADR
    • Size requirements
    • Sensitivity
    • Temperature range
    • Heat dissipation range
    • Strength and dynamic of magnetic fields
    • Time Scale for Project

Assignments:

Fluxgate:
Michael & Andrew

Hall Effect:
Kristen

Moving Coils:
Kat

Other MAGs:
Chris

© Olin College NASA Study 2004