Transcript Design Status of IOT for ILC

Design Status of IOT for ILC
Hyoung Suk KIM
KNU
KOREA
CCAST ILC Accelerator Workshop and
1st Asian ILC R&D Seminar under JSPS Core University
November 7, 2007
MBK(Multi-Beam Klystron) for ILC
10MW MBK parameters
ILC RDR
10MW SBK
5MW IOT
10MW MBK (64kV)
Pros. and Cons.
Pros.
- Low cost
- Easy installation in the
tunnel
- No expensive modulator
- Economic maintainability
Cons.
- No L-band yet
- Not easy to increase freq.
- Need fund to make
prototype and industrialize
Klystron
Electron Beam Velocity Modulation
Output
Input
Cathode
-
Collector
overtemp
+
Filament
-
+
-
-
+
Focusing
Interlocks
+
Modulator
+
-
+
Body current
IOT
Electron Beam Density Modulation
Cathode
-
Output
Input
Collector
overtemp
+
Filament
+
-
Bias Voltage
Interlocks
-
+
Body current
-
+
Power Supply
What’s new?
•
•
•
•
•
Planar IOT (Inductive Output Tube)
Horizontal Design
L-band (1.3GHz) 5MW Tube
Calculation of Design Parameters
Feasible RF interaction Cavity
Equivalent Circuit Approximation
• Capacitance
i(t)
– from Gauss’ Law
V(t)
• Inductance
– from Ampere’s Law
• Resonance Frequency
• Unloaded Q
C
R
Lumped-constant circuit
L
HOM IOT
L-band HOM IOT Cavity
Ez field in the interaction region
S-parameters of L-band HOM IOT
H field in the interaction region
Ez field in the interaction region
f(cold)=1.1GHz (MAGIC)
Design Specifications
Beam Voltage
55 kV (nom)
Beam Current
123 A (nom)
Frequency
1.3 GHz
Gain
- dB (min)
Efficiency
~70 % (nom)
Cathode Loading
<1.0 A/cm2
Pre-modulated Electron Beam
I
I0
0
T/2
T
3T/2
2T
5T/2
Pre-modulated electron beam in current v.s. time ;
cut-off sinusoidal current which is used in class B operation,
I = I0 MAX(sinwt, 0).
t
Electron Gun
Cavity Design
cathode area = 300cm2
S-parameters of the RF resonator ; real (red) and
imaginary (blue) values which shows us its cold
frequency is 1.255GHz. (TM01-mode)
Electric field intensity in RF resonator on the gapcentered cross section. This shows the cavity has
TM01-mode where the resonator frequency is
1.255GHz in the absence of conductivity of cavity and
electron beam.
Schematic Representation for Definition
ty
t
t ; snapshot time
tx ; transit time
ty ; departure time
T0 ; gap (d) transit time
eee-
resonator
grid 1
resonator
grid 2
e-
t = ty + tx
e-
e-
0
d
z
t-T0
0
T0
tx
Schematic representation for the definition of snap shot time (t), transit time (tx) to z, departure time (ty).
Electron Beam Dynamics in 1-D
Output Power & Gap Field
Gap Field & Efficiency
From resonator field theory,
SUMMARY
 Design efforts for IOT (ILC) started.
 This feasibility study to design IOT for ILC looks very positive.
 Design parameters are calculated along with its performance.
 Final electrical design will be released soon.
And industrialization will be considered. (Toshiba,CPI,…)
 After fund is available, more flexible design will be performed
and more resources will be put in.