1
July 2009
11.424 GHz High Gradient Testing of a
T18 TW Structure Using a Fast Response
Protection and Power Recirculating System
Work performed under the auspices of the U.S. Department of Energy SBIR
Grant No. DE-FG02-08ER85197
HAIMSON RESEARCH CORPORATION
2
July 2009
Objective:
To Compare the High Gradient Performance of
a Dual Feed T18 TW Linac Structure when
Driven by a Resonant Ring Power Amplifier
and when Load Terminated and Excited
Directly with a High Power Klystron.
HAIMSON RESEARCH CORPORATION
July 2009
Content:
1. Describe Advantageous Operating Characteristics of
Resonant Ring Driven TW Linacs.
2. Discuss Design Features of the Planned 11.424 GHz
Power Recirculating System
dart
HAIMSON RESEARCH CORPORATION
4
July 2009
RF
LOAD
BRIDGE
BALANCE
PROCESSOR
RF
SOURCE
RF MONITOR
RF
BRIDGE
1
PS
2
3
PA = (1 + n)PS
ELECTRON
SOURCE
4
TEST LINAC
PL
PF = nPS
SPECTROMETER
HAIMSON RESEARCH CORPORATION
5
July 2009
NORMAL LINAC OPERATION
RF Source Power
Bridge Load Power
Linac Input Power
Linac Reflected Power
WITH ARC IN LINAC
Showing that when an Arc Occurs in the Linac, the
Linac Input Power (blue) is Rapidly Truncated and,
for the Remaining Portion of the Klystron RF Pulse
the Bridge Input Power (red) is Automatically
Directed into the Bridge Load (green).
Thus, the Linac Power Amplifying Bridge Assists
in Automatically Protecting both the RF Source
and the High Gradient Linac Structure.
“Design Features and Initial RF Performance of a Gradient Hardened 17 GHz TW Linac Structure,”
in Advanced Accelerator Concepts, AIP Conf. Proc., No. 1086, pp. 464-469, 2008.
HAIMSON RESEARCH CORPORATION
6
July 2009
View of All-Copper 17 GHz Linac Structure and 4X Peak Power Amplifier System.
HAIMSON RESEARCH CORPORATION
7
July 2009
HAIMSON RESEARCH CORPORATION
8
July 2009
LINAC POWER BUILDUP, PA/PS
3.0
99.11%
OverCoupled
2.5
C = .613
89.7%
C = .831
2.66
PL/PS = 0
2.20
2.0
98.8%
PL/PS =
99.90%
17.3%
1.5
Critically
Coupled
1.0
f = 11.424 GHz
0.5
0
Bridge Coupling Coefficient = C
Feedback Loop Loss,  = 2.05 dB
0
100
200
300
400
500
BUILD-UP TIME FOR A 38ns LOOP TRANSIT (ns)
HAIMSON RESEARCH CORPORATION
July 2009
9
0.7
3.5
f = 11.424 GHz
(PL/PS)
n = 1.98
0.5
613
.650
2.39
1.37
3.0
.
2.05
1.66
C = .579
0.4
2.5
2.0
(PA/PS)
0.3
1.5
PS = Source Power
n = Bridge Ratio
 = Loop Loss (dB)
C = Bridge Coupling Coefficient
Loop Transit Time = 38 ns
0.2
0.1
0
0
50
100
150
200
250
300
350
400
450
1.0
LINAC INPUT POWER (PA/PS)
RF LOAD POWER (PL/PS)
0.6
 = 1.78 dB
0.5
500
0
550
ELAPSED TIME (ns)
HAIMSON RESEARCH CORPORATION
10
July 2009
Mode Converter Used with the T18 Structure
Ez Field Pattern at f = 11424 MHz
HRC 7131 Resonant Ring Phase Study 03/13/09
HAIMSON RESEARCH CORPORATION
11
July 2009
Design Parameters of an 11.4GHz Dual Resonant
Ring System Configured for High Gradient Testing
of the CLIC/KEK/SLAC (T18) Linac Structure
System Operating Frequency . . . . . . . . . 11.424 GHz
Test Linac Attenuation Parameter (). . . . . .
Test Linac Harmonic Mean
Group Velocity (vg)hm . . . . . . . . . . . .
0.21 Np
0.016 c
Total Loss in Feedback Loop () . . . . . . . .
2.05 dB
Resonant Ring Transit Time . . . . . . . . . .
38 ns
Resonant Ring Total Phase Length . . . . . .
Resonant Ring Phase Dispersion . . . . . . .
WR90 Rectangular Waveguide
Phase/Length Relationship . . . . . . . . .
Length/Phase Relationship . . . . . . . . .
17280 deg
15 deg/MHz
11.2 deg/mm
.089 mm/deg
HAIMSON RESEARCH CORPORATION
12
July 2009
RF Bridge Ratio [n=(TC/C)2] . . . . . . . . . .
1.66
RF Power Buildup (n+1) . . . . . . . . . . . .
2.66
RF Bridge Transmission Coefficient
{TC= [n(n+1)]1/2} . . . . . . . . . . . . . .
0.790
RF Bridge Coupling Coefficient
[C=(n+1) -1/2] . . . . . . . . . . . . . . . .
0.613
Linac Steady-State Input Power (PA) . . . . .
65 MW
Unloaded Average Accelerating Gradient . . .
108 MV/m
Klystron Power . . . . . . . . . . . . . . . .
26 MW
HAIMSON RESEARCH CORPORATION
13
July 2009
An 11.424 MHz Dual Resonant Ring System for High Gradient Testing
CLIC/KEK/SLAC T18 Structures
Power Distribution to Achieve an Unloaded Accelerating Gradient of 108 MV/m
21.4 MW
32.5 MW
21.4 MW
32.5 MW
26 MW
HAIMSON RESEARCH CORPORATION
14
July 2009
-4.77 dB (1/3) Directional Coupler
0.900”
2.4076”
0.5381”
1.4104”
0.4928”
r=0.250”
r=0.0625”
@ 600 MW, 1.435” height:
|Esmax| = ~45.6 MV/m
|Hsmax| = ~160 kA/m
C. Nantista ’03
15
July 2009
HAIMSON RESEARCH CORPORATION
16
July 2009
With Adaptive Meshing
M = 1177344
21/15/10R6
HAIMSON RESEARCH CORPORATION
17
July 2009
HAIMSON RESEARCH CORPORATION
18
July 2009
11.424 GHz High Gradient Testing of a
T18 TW Structure Using a Fast Response
Protection and Power Recirculating System
Work performed under the auspices of the U.S. Department of Energy SBIR
Grant No. DE-FG02-08ER85197
HAIMSON RESEARCH CORPORATION
19
AAC2008
s11cfsh5.epw
TRIPLE
HYBRID
M
(PA/PS)
0.8
 = 1.25 dB
 = 1.35 dB
(PL/PS)
4
3
TEST DATA
0.4
M
0.2
R
0
50
PSh
DC
 = 1.15 dB
0.6
0
R
5
W
100
2
f = 17.1 GHz
n = 3.0
c = 0.5
 =FTotal Loss in
Feedback Loop
DC
150
200
ELAPSED TIME (ns)
1
LINAC INPUT POWER (PA/PS)
17 GHz TWRK
RF LOAD POWER (PL/PS)
1.0
0
250
F
(b)
R
F
LOAD
DC
HYBRID
(A)
R
DC
F
FC
INJECTOR
22 CAVITY TEST LINAC
94 CAVITY TW LINAC
SPECTROMETER
LOAD
F
FC
DC
R
(B)
F
R
HYBRID
LOAD
DC
HAIMSON RESEARCH CORPORATION