1. 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

2. MBK(Multi-Beam Klystron) for ILC
10MW MBK parameters
ILC RDR

3. 5MW IOT
10MW SBK
10MW MBK (64kV)

4. Pros. and Cons. Pros. Cons. Low cost Easy installation in the tunnel
No expensive modulator
Economic maintainability
No L-band yet
Not easy to increase freq.
Need fund to make
prototype and industrialize

5. Electron Beam Velocity Modulation
Klystron
Electron Beam Velocity Modulation
Input
Output
Cathode + - + - + - + -
Collector
overtemp + -
Filament
Focusing
Body current - +
Interlocks
Modulator

6. Electron Beam Density Modulation
IOT
Electron Beam Density Modulation
Cathode + -
Power Supply
Input
Bias Voltage
Filament
Interlocks
Collector
Output
Body current
overtemp

7. What’s new? Planar IOT (Inductive Output Tube) Horizontal Design
L-band (1.3GHz) 5MW Tube
Calculation of Design Parameters
Feasible RF interaction Cavity

8. Equivalent Circuit Approximation
Lumped-constant circuit
i(t)
V(t) C R
Capacitance
from Gauss’ Law
Inductance
from Ampere’s Law
Resonance Frequency
Unloaded Q L

9. HOM IOT S-parameters of L-band HOM IOT L-band HOM IOT Cavity
Ez field in the interaction region
f(cold)=1.1GHz (MAGIC)
Ez field in the interaction region
H field in the interaction region

10. 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

11. Pre-modulated Electron BeamI0 I
Electron Gun
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).

12. 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 gap-centered 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.

13. Schematic Representation for Definitionty tx t T0
t-T0
t ; snapshot time
tx ; transit time
ty ; departure time
T0 ; gap (d) transit time
t = ty + tx e-
resonator
grid 1
grid 2 z d
Schematic representation for the definition of snap shot time (t), transit time (tx) to z, departure time (ty).

14. Electron Beam Dynamics in 1-D

15. Output Power & Gap Field

16. Gap Field & Efficiency
From resonator field theory,

17. 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.