booster bpm’s
DESCRIPTION
Booster bpm’s. Jim Crisp 3/29/06. Plate width and linearity. with the response linearized along the axis 60 and 20 degree plates become nonlinear in the corners 40 degree plates have the least distortion calculate 0.5db/mm (booster bpm’s are 0.52db/mm). 50 or 25 ohms. - PowerPoint PPT PresentationTRANSCRIPT
Plate width and linearity
0
10
20
30
40
50
60
70
80
0 10 20 30 40 50 60 70 80
40 degree plates
0
10
20
30
40
50
60
70
80
0 10 20 30 40 50 60 70 80
60 degree plates
with the response linearized along the axis 60 and 20 degree plates become nonlinear in the corners40 degree plates have the least distortioncalculate 0.5db/mm (booster bpm’s are 0.52db/mm)
5
2135][
BA
BA
BA
BAmmX
50 or 25 ohms
• The even mode impedance is most important• 50 ohm 40 degree plates won’t fit in the proposed magnet (60 degree plates worse)
– 3.916” plate ID for 5.465” bpm OD• 25 ohm, 40 degree plates will fit
– 4.5” plate ID 5.228” bpm OD with 1/8” wall
30.0
40.0
50.0
60.0
70.0
5 5.25 5.5 5.75 6
bpm pipe ID [inches]
char
acte
rist
ic i
mp
edan
ce [
oh
ms]
even
odd
40 deg plates
4 3/8" plate ID5.408" ID5.533" OD
50ohm 40deg plates 5.465" bpm OD 1/16" w allestimated plate ID 3.916"
25ohm 40deg plates w ith 4.625" plate ID1/8" w allestimated bpm OD 5.228"
Equivalent bpm• Current booster bpm’s
– 4.625” plate ID, 60 degrees wide, 6” long, 6” bpm OD, – 52.9 ohms even, 44.2ohms odd mode– Vplate/Ibeam 1.4 ohms at 53MHz– 0.52db/mm 30-50MHz and 0.48db/mm at 200MHz
• Proposed bpm– 4.5” plate ID, 40 degrees wide, 16” long
• Ideal (60/40)(50/25)6” = 18” correction magnet 17.5” flange to flange– 25 ohms even 24.2 ohms odd– Vplate/Ibeam = 1.25 ohms at 53MHz (about 10% less)– 0.50db/mm
MHzatc
lZ
I
V
Idt
dtZV
MHzl
c
RCf
pfcZ
l
Z
tC
detectorcapacitive
obeam
plate
beamoplate
ooplate
534.1360
60
360
60
31322
1
1.10
)(
534.1360
60
sin360
60
smallc
l
MHzatc
lZ
c
lZ
I
V
detectorstripline
o
obeam
plate
Beam intensity range• 25 ohms, 40 degrees wide, 16” long
– (Correction magnet is 17.5” flange to flange)• Rf module dynamic range -23.5 to +18.5dbm
– -35 to +27dbm for AM to PM rf module– +1.5db for 100ft RG8 cable– +/-10db for +/-20mm position
• working range of beam intensity– 8.4 to 1060e10– (about the same as now)
dbmVV
AmpsI
eNmRR
cNeMHzI
plate
beam
beam
0.185.2
0.2
13189.752
2)53(
Frequency response
• Peak at wl/c = pi/2 (plates 1/4 wavelength long)– 185MHz for 16” and 492MHz for 6” plates
• Same response for terminated, open, or shorted stripline– 200MHz linac beam 5.00/2.75 ohms (present/proposed)– 37.9MHz at 400MeV 1.06/0.93 ohms– 52.8MHz at 8GeV 1.40/1.20 ohms
0
2
4
6
8
10
0 50 100 150 200 250 300 350 400 450 500
frequency [MHz]
Vp
late
/Ib
eam
[o
hm
s]
40deg, 25ohm, 16" long
60deg, 50ohm, 6" long
Use 50ohms at bpm output to terminate stripline
rf modules
-10
-5
0
5
10
-40 -20 0 20 40
A/B [mm]
A/B
- c
alc(
A/B
) [m
m]
A+B greater than -40db
-10
-5
0
5
10
-60 -40 -20 0 20
A+B [db]
A/B
- c
alc(
A/B
) [m
m]
-24
-20
-16
-12
-8
-4
0
4
8
12
16
20
24
-60 -40 -20 0 20
A+B [db]
calc
A/B
[db]
10
14.1
0
4tanln10ln
20
1
0
01
C
F
V
VVFCFB
A
db
(MI 0.48db/mm Hor, 0.42db/mm Ver)
MI rf module, similar for booster
Wall thickness and magnetic fields
• magnetic fields will be attenuated and delayed inside bpm• round pipe acts like low pass filter (approximate)
– n = 2 for dipole (4 for quadrupole etc)– ρ = 9.0e-7 ohm-m for stainless steel– R = 3” radius– t = 1/8” wall thickness
– f ~ 942Hz t ~ 170usec
– The 4 plates will also distort a changing magnetic field above this frequency
– Frequency where 1/8” = skin depth• f = 22.6KHz
• What are the frequency components of the correction fields?
– (30-50MHz external magnetic fields will never reach the plates)
tR
nf
2
f
Measured fields in pipe• 1/8” wall 2” ID Aluminum pipe• Solid is calculated using Mafia – Ostiguy• Red curve from simple formula• Points are measured with hall probe
-100
-80
-60
-40
-20
0
10 100 1000 10000 100000
freq [Hz]
amp [db]
1/8" wall 2" ID Al
A few details• Proj 22 Task 1.02.03.01• deliver nearly the same signal to the rf modules
– Lowest intensity 1 turn of 30mA or about 40e10• 24 long and 24 short locations (use same bpm) 60 magnets will be made• Need survey fiducials to measure bpm location in tunnel
– Use same fiducials on bpm test stand– survey position and rotation tolerances?
• Allowable wall thickness / bandwidth of correction fields– Rise times of 2 msec– Eddy current heating may be a problem (correctors ramped at 15Hz)
• radiation exposure over the expected life time?– Few locations measured at 20KRad/month (MRad/lifetime)
• Vacuum acceptance criteria– Flanges should be angled to match bend magnet– Assembly may require a bellows
• Bpm should be made very reliable and thoroughly tested before installation, requires replacing magnet to change
• May request cable strain relief bracket on magnet• Prototype bpm for test June 2006• First 24 required February – April 2007• Installation June 2007