RFQ Matcher

What am I doing this time?!

• Concerned that modulations and matcher affect field flatness and frequency

• These are very small features

• How much do they affect bulk 4m RFQ?

Matcher Geometry

Plane vanes Matcher On

Matcher E-field

Plane vanes Matcher On

First three modes’ B-fields

First three modes’ E-fields

Mode Frequencies: Matcher On/Off

Cold Model Field Flatness

Four Metre RFQ Field Flatness

Variation of Finger Length

10mm diameter fingers of varying length15mm in x and y from beam axis

Variation of Finger Position

10mm diameter, 80mm long fingersVary finger distance from beam axis

Conclusion

• Matcher does make large scale differences

• Modulations will do the same

• Need to stop using plane-vane models• End fingers help, but need to pay attention

to field flatness

• Leads to complicated tuning!