rfq tuning method last results
DESCRIPTION
RFQ Tuning Method last results. IPHI-SPL collaboration meeting - CERN 28 & 29 /04/2003. CEA/DSM/DAPNIA/SACM. V [kV]. 4. Closest dipole modes frequencies. 3. Dipole components presence within the accelerating mode. f + D - f Q = f Q - f - D. - PowerPoint PPT PresentationTRANSCRIPT
CEA Saclay / F. SIMOENS - A. FRANCE - J. GAIFFIERRFQ tuning method 10/02/2003
RFQ Tuning Methodlast results
IPHI-SPL collaboration meeting - CERN 28 & 29 /04/2003
CEA/DSM/DAPNIA/SACM
CEA Saclay / F. SIMOENS - A. FRANCE - J. GAIFFIERRFQ tuning method 10/02/2003
What do we electromagnetically tune ?
2. Accelerating voltage profile : Vp(z)
|(uQ(z)-Vp(z))/Vp(z)|< 10-2
4. Closest dipole modes frequencies
f +D - fQ = fQ - f -
D
352.21 MHz1. Resonance Frequency fQ :
3. Dipole components presence within the accelerating mode
|uS(z)/uQ(z)|< 10-2 |uT(z)/uQ(z) |< 10-2
80
90
100
110
120
130
0 1 2 3 4 5 6 7 8
V [kV]
z [m]
CEA Saclay / F. SIMOENS - A. FRANCE - J. GAIFFIERRFQ tuning method 10/02/2003
S = [ -1/2, 0, 1/2, 0]
T = [ 0, -1/2, 0, 1/2] S
0V
0V
Et
Ht
R(Hz)
+
+
-
-
Mode S et T (ST)
distribution S
dipole Modes
Q = [ -1/2, 1/2, -1/2, 1/2]
Mode Q
0V 0V
0V 0V
-
-
+ +
Et
Ht
R(Hz)
Quadripole Mode focalisation Kpq = 352,2 MHz
…
CEA Saclay / F. SIMOENS - A. FRANCE - J. GAIFFIERRFQ tuning method 10/02/2003
Central region
What do we mechanically tune ?
1. Slug tuners
End regions
2. « dipole » rods
3. Plate thickness
CEA Saclay / F. SIMOENS - A. FRANCE - J. GAIFFIERRFQ tuning method 10/02/2003
The tuning tools that we have developed
1. Model
What is the
ideal RFQ ?
Diagnosis
Treatment
2. Test bench
e.l.m. parameters
of the real RFQ
3. Spectral analysis Defaults real RFQ / ideal RFQ
e.l.m. parameters mechanical devices
5. Mathematical formalism
4. Cold-model Frequencies
Field distribution
1. Slug tuners
2. Dipole rods
3. End plates
Fast tuning High accuracy
CEA Saclay / F. SIMOENS - A. FRANCE - J. GAIFFIERRFQ tuning method 10/02/2003
Our model & the associated spectral analysis
Refer to :A. France, F. Simoens, “Theoretical Analysis of a Real-life RFQ Using a 4-Wire Line Model and the Spectral Theory of Differential Operators.”, EPAC2002 Conference (Paris), June 2002
Coupled, inhomogeneous,
4-wire line equivalent circuit
Central region End regionsEnd regions
Eigen functions (orthogonal basis)
= { vQi(z), vSj(z), vTk(z) }
voltage base functions
'2
2' Vc
VM
M = hermetian operator (tM=M)
Boundary conditions
Eigen values (R+) = resonance frequencies fQi, fSj, fTk
d2U/dz2 – A U = - (/c)2 U
CEA Saclay / F. SIMOENS - A. FRANCE - J. GAIFFIERRFQ tuning method 10/02/2003
Comparison measurements / model / 3d simulations
Refer to : F. Simoens, A. France, O. Delferrière, “An Equivalent 4-Wire Line Theoretical Model of Real RFQ based on the Spectral Differential Theory”, CEA-SACLAY, LINAC Conference (Gyungju, Korea), August 2002
3
2
4
L
1
C
1
L
2
L
3C
3L
4C
4
ModelMeasurements 3d simulations
-1,5
-1,0
-0,5
0,0
0,5
1,0
1,5
0,0 0,5 1,0 1,5 2,0
vQ6 "2+2"
1 2 1 2
-1,5
-1,0
-0,5
0,0
0,5
1,0
1,5
0,0 0,5 1,0 1,5 2,0
vQ5 "2-2"
1 2 1 2-
-4,0
-3,0
-2,0
-1,0
0,0
1,0
2,0
3,0
4,0
0,0 0,5 1,0 1,5 2,0
uQ "2-2"
1 2 1 2-
-4,0
-3,0
-2,0
-1,0
0,0
1,0
2,0
3,0
4,0
0,0 0,5 1,0 1,5 2,0
uQ "2+2"
1 2 1 2
+
-1,0
-0,5
0,0
0,5
1,0
0 500 1000 1500 2000
Hz
1 2 1 2-
-1,0
-0,5
0,0
0,5
1,0
0 500 1000 1500 2000
Hz
1 2 1 2
+
CEA Saclay / F. SIMOENS - A. FRANCE - J. GAIFFIERRFQ tuning method 10/02/2003
Slug tuners : fast simultaneous convergence
86 000
88 000
90 000
92 000
94 000
96 000
98 000
100 000
102 000
0,0 0,5 1,0 1,5 2,0
IPHI Vp
0
uQ(z) [u.a.]
-15
-10
-5
0
5
10
15
0 0,5 1 1,5 2
0
uT(z) [u.a.]
-15
-10
-5
0
5
10
15
0 0,5 1 1,5 2
0
uS(z) [u.a.]
fQ
0 350,62 MHz
86 000
88 000
90 000
92 000
94 000
96 000
98 000
100 000
102 000
0,0 0,5 1,0 1,5 2,0
1
-15
-10
-5
0
5
10
15
0 0,5 1 1,5 2
1
-15
-10
-5
0
5
10
15
0 0,5 1 1,5 2
1
1 352,18 MHz
86 000
88 000
90 000
92 000
94 000
96 000
98 000
100 000
102 000
0,0 0,5 1,0 1,5 2,0
2
-15
-10
-5
0
5
10
15
0 0,5 1 1,5 2
2
-15
-10
-5
0
5
10
15
0 0,5 1 1,5 2
2
2 352,22 MHz
"A " "B"
RFQ 2x1m
-0,2.10-2<(uQ-Vp)/Vp<0,2.10-2
-0,4.10-2<uD/uQ<0,4.10-2-6,4.10-2<(uQ-Vp)/Vp<3,4.10-2
-9,2.10-2<uD/uQ<10,6.10-2
Ref: F. Simoens, A. France, J. Gaiffier, “A New RFQ Model applied to the Longitudinal Tuning of a Segmented, Inhomogeneous RFQ with Highly Irregularly Spaced Tuners”, EPAC2002 Conference (Paris), June 2002
CEA Saclay / F. SIMOENS - A. FRANCE - J. GAIFFIERRFQ tuning method 10/02/2003
Dipole rods length adjustment
Refer to :F. Simoens, A. France, “Tuning procedure of the 5 MeV IPHI RFQ”, CEA-SACLAY, LINAC Conference (Gyungju, Korea), August 2002
Good correspondence between the measured and the ‘ideal’ dipole mode frequencies
Matching of the equivalent end loads
A new tuning criteria : ‘quadratic shift frequency’
SegmnSegmn nnffndf 22
When df(n)real RFQ df(n)ideal RFQ
0,0
0,5
1,0
1,5
2,0
2,5
0,0 0,5 1,0 1,5 2,0z [m]
U4
U2
U1U3
steep slopes
before dipole rods tuning
0,0
0,5
1,0
1,5
2,0
2,5
0,0 0,5 1,0 1,5 2,0z [m]
U1
U4
U2
U3
straightened slopes
after dipole rods tuningVoltage profiles of the first dipole mode
CEA Saclay / F. SIMOENS - A. FRANCE - J. GAIFFIERRFQ tuning method 10/02/2003
End plate thickness adjustment
Refer to :F. Simoens, A. France, “Tuning procedure of the 5 MeV IPHI RFQ”, CEA-SACLAY, LINAC Conference (Gyungju, Korea), August 2002
= L x f [m.MHz] L = RFQ half-length
f = (mismatched resonance freq.) - (nominal cut-off freq.)
End region mismatch characterization : parameter
0,05
m.M
Hz
< 1
0 m
m
0,33
m.M
Hz
<
20
mm
-0,2
4 m
.MH
z
5
< 0
mm
z
v an e
end-
plat
e
Nominal mid-position thickness 0 m.MHz
Example of the IPHI RFQ cold-model end region
adjustment range [-0,24 m.MHz , +0,33 m.MHz]
CEA Saclay / F. SIMOENS - A. FRANCE - J. GAIFFIERRFQ tuning method 10/02/2003
End plate thickness adjustment
Refer to :F. Simoens, A. France, “Tuning procedure of the 5 MeV IPHI RFQ”, CEA-SACLAY, LINAC Conference (Gyungju, Korea), August 2002
Parameter extraction from measurements
#1 #2 #3 #4 #5 #6 #7 #8 #9 #10 #11 #12
End #2End #1
Spectral analysis
Slugs are moved at some distance of the end being tunedi.e. for end#1, in planes #6, 7 and 8 of segment #1 = set of different voltage excitations
end#1 plate thickness
Average [m.MHz]
Std. Dev. [m.MHz]
0 -0.120 0.032
10 0.001 0.055
20 +0.300 0.086
The nominal plate thickness is well-adjusted,
CEA Saclay / F. SIMOENS - A. FRANCE - J. GAIFFIERRFQ tuning method 10/02/2003
ConclusionLast results
• The agreement between measurements, 3d simulations and our model validates our mathematical formalism.
• The tuning procedures of the different mechanical devices have been developed and experimentally validated.– In a 2-m long RFQ, we have achieved relative voltage error lower
than 10-2 within 3 steps of slug tuners displacements.– For the dipole rods adjustments, a new practical tuning criteria has
been introduced, that ensures the convergence of tuning.– The end region mismatch can be characterized from a set different
voltage excitations and directly related to the end plate thickness.
Studies in progress• Chronology of the different tuning procedures in the context of
the RFQ machining and assembling steps.• RF power coupling (iris / loop).