## Feature #1670

### Magnetic Axis of FC2, USS and DSS

Start date:

08 April 2015

Due date:

% Done:

100%

Estimated time:

**Related issues**

#### Updated by Blackmore, Victoria over 8 years ago

This issue summarises what we know (so far) about the magnetic axis of FC2, USS and DSS and the cross-checks that have been made.

- Item #2: FC2 current axis estimates
- Axis in mapper co-ordinate system
- Axis w.r.t. fiducials in R9 co-ordinate system
- Axis w.r.t. PCD

- Item #3: USS current axis estimates
- Axis in surveyed co-ordinate system

- Item #4: DSS current axis estimates
- Axis in surveyed co-ordinate system

- Item #5: Method summary
- Item #6: Alternative axis cross-check using |B|

...

#### Updated by Blackmore, Victoria over 8 years ago

## FC2 axis estimates¶

The mapper was centred and surveyed w.r.t. the centre defined by the inner flanges of the warm bore. This was related to the fiducials by a second survey within the R9 network of survey nests. First determine the axis in the mapper's co-ordinate system, then translate to the R9 network.

- Define '_z_' as the longitudinal co-ordinate
- Define '_x_' as the horizontal co-ordinate
- Define '_y_' as the vertical co-ordinate

### Magnetic axis in the mapper system¶

- The magnetic axis is assumed to be a straight line (as the coils are wound on a common bobbin), which has the form:
*x = az + b**y = cz + d*

*a*and*c*are rotations around the*y*and*x*axes respectively,*b*and*d*are offsets.- Within the mapper system, the two flanges are at approximately
*z*= 918mm and*z*= 1762mm (the latter being the side with the inner flange). - Have determined the
*(x, y)*co-ordinates of the axis at these locations, and the equation of their lines, at different currents and in Flip and Solenoid mode.

#### Updated by Rogers, Chris over 8 years ago

#### Updated by Rogers, Chris over 7 years ago

**Status**changed from*In Progress*to*Closed***% Done**changed from*50*to*100*

I think this is closed... can reopen a new issue after the realignment work done in Feb