1. Stray field corrector: conceptual design
C. Gohil
(24/11/17)
FONT Meeting - C. Gohil, Stray Field Corrector: Conceptual Design
24/11/2017

2. Basic Idea Steps: Stray field induces a voltage 𝜀.
𝜀 is used to calculate 𝜀 𝑐𝑜𝑟𝑟 .
A magnetic field (corrector field) is generated by the corrector coil by applying 𝜀 𝑐𝑜𝑟𝑟 .
𝜀 is now the voltage induced from the stray field and corrector field.
Reiterate…
Stray Field:
5nT, 25 Hz
10 kHz sampling frequency
Measurement coil:
records voltage 𝜀
Corrector coil:
induced voltage 𝜀 𝑐𝑜𝑟𝑟
FONT Meeting - C. Gohil, Stray Field Corrector: Conceptual Design
24/11/2017

3. Standard Feedback loop
N. B. There are two inputs for each component. ⟹
System is well-posed if this is non-singular
FONT Meeting - C. Gohil, Stray Field Corrector: Conceptual Design
24/11/2017

4. Stray field corrector feedback loop
𝜀 𝑐𝑜𝑟𝑟
Corrector coil
Measurement coil:
records voltage 𝜀
Corrector coil:
induced voltage 𝜀 𝑐𝑜𝑟𝑟 d 𝜀
Measure-ment coil
Steps:
Stray field induces a voltage 𝜀.
𝜀 is used to calculate 𝜀 𝑐𝑜𝑟𝑟 .
A magnetic field (corrector field) is generated by the corrector coil by applying 𝜀 𝑐𝑜𝑟𝑟 .
𝜀 is now the voltage induced from the stray field and corrector field.
Reiterate…
FONT Meeting - C. Gohil, Stray Field Corrector: Conceptual Design
24/11/2017

5. Stray field corrector feedback loopn d v u
Measurement coil, F
Corrector coil, P
Controller, C y n
x1= d +Px3
x2= n + Fx1
x3= Cx2 d
Measurement coil, F v
Controller, C ⟹ x1 x2 y
Corrector coil, P x3 u
Determinant = -1 + PFC
FONT Meeting - C. Gohil, Stray Field Corrector: Conceptual Design
24/11/2017