FPC hook – revisited April 2014
OLD VERSION
LATEST NEW VERSION
Increased fm to enlarge coupling. Hook does not
need to penetrate so deep into port tube.
Enlarged cross section for better heat flow (from
circular to elliptical cross section).
Round section.
QextFPC --
P0FPC
W
4.87e5
4.87e5
600
106
Too large power loss difficult to cool down.
High amount of radiated heat in
consequence.
- Field offset = 0.22mm
- Minimum distance of 6.25mm between
hook end plate and wall. Multipacting?
- Cooling along the hook?
Power losses in flange gasket of HOM port tubes
Use RF seal copper gasket for:
1) significant reduction of power losses
in flanges interconnection and
2) enhanced leak tightness.
Port tube
Flange
0.003m
0.031m
RF-seal gasket
Filter must be detachable!
Power losses in flange gasket of HOM port tubes
Vdefl=1.038MV 
Evaluated power loss for a 3mm-height ring
Top HOM1
at a distance from the cavity center that
varies from 211 to 219mm
(between hook capacitance
219mm
211mm
and first inductive rod).
Gasket
position*
mm
211-214
214-217
217-220
220-223
223-226
226-229
Top HOM1
Bot HOM2
Bot HOM3
Power loss (in 3mm heigth I.D. 62mm Cu gasket)
W
7.313727537 7.916753808 7.959449013
6.848096523 7.448041806 7.559266434
6.516323567 7.108316969 7.247232251
6.383518757 6.977828909 7.112640124
6.549276743 6.958551969 7.234703821
7.071746576 7.373582196 7.789950541
*For Vdelf=3.34MV.
Anomalous skin effect of copper at 2K and 400MHz
(Rs~0.8mOhm) and surface roughness contribution (30%).
7 W in each port gasket…
•
Nb-coated copper gaskets?
•
Extend coax line between hook and filter?
Bot
HOM3
Bot
HOM2
Power losses in flange gasket of HOM port tubes
Plus reduce HOM port length
for clearance purposes
Move first inductive
rod away from hook