1. Grounding Studies Metal box sensor SVX4/hybrid Analog cable GND(20W)
Signal return
L0 support
Kapton flex
GND
hybrid GND
sensor GND
Signal ground

2. L0 prototype module
sensor ground
hybrid ground

3. Effect of Grounding Structure inside the aluminum box. Hybrid only
Sensor only
Both hybrid and sensor

4. Equivalent (?) circuit (cont’d)
Metal box
sensor
SVX4/hybrid
Signal ground
Signal return
L0 support
Kapton flex
GND
hybrid GND
sensor GND
Connection important
Smaller inductance (or smaller loop)
Least impedance = least inductance for high frequency (not resistance).

5. After putting extra grounding plane
Note! Still the hybrid grounding is not perfect in terms of getting low inductance… but the effect of the extra ground plane is clearly seen.
Single ground at hybrid
Common ground at both hybrid and sensor

6. Importance of low inductance connection
1 wire between hybrid and the extra grounding plane.
3 wires
4 wires

7. Low inductance connection (cont’d)
2 wires (~4cm)
2 wires (~2cm)

8. Reducing the inductance
Having lower inductance connection to GND seems crucial.
L ~ (wire) length/radius: M=ml/2p[log(2l/r)-1]
L = Y/I
Y ~ area of the closed circuit
People know these rules well, but sometimes forget to apply.
But these rules are always critical for any grounding connections, both locally and generally.
better

9. Low-pass filter board for HV
How do we achieve????????????
Sensor grounding.
The sensor and hybrid need to be connected through rigid ground plane. This should work also as a shielding  extension of kapton flex with copper mesh embedded.
Need to decide; multi point ground vs single point ground at hybrid end.  Marvin prefers multi point ground to avoid an accidental (capacitive) coupling which screws up the single point grounding scheme.
Carbon Fiber
Flex
Circuits
Vias
Low-pass filter board for HV
Sensor
Copper Mesh

10. Grounding scheme for hybrid
Low inductance grounding connection to hybrid is very important (let me repeat).
Direct connection to the support structure.  minor concern on the L0B hybrids.
Another option? Hybrid support rail as grounding plane.
Kapton flex for the connection