Hyoung Suk KIM

KNU

KOREACCAST ILC Accelerator Workshop and

1st Asian ILC R&D Seminar under JSPS Core University

November 7, 2007

Design Status of IOT for ILC

10MW MBK parametersMBK(Multi-Beam Klystron) for ILC

ILC RDR

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

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

Klystron

CathodeCollector

Electron Beam Velocity Modulation

+-

Modulator

Input Output

+- +- +- +-Focusing

+-Filament

Body current

overtemp

Interlocks

IOTElectron Beam Density Modulation

Cathode

+-

Power Supply

Input

Bias Voltage

+-Filament

Interlocks

Collector

Output

+-

Body current

overtemp

+ -

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– from Gauss’ Law

• Inductance– from Ampere’s Law

• Resonance Frequency

• Unloaded Q

Lumped-constant circuit

i(t)

V(t) C R L

HOM IOT

Ez field in the interaction region H field in the interaction region

L-band HOM IOT Cavity S-parameters of L-band HOM IOT

Ez field in the interaction regionf(cold)=1.1GHz (MAGIC)

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

Design Specifications

Pre-modulated Electron Beam

T/2 T 3T/2 2T 5T/2t

I0

I

0Pre-modulated electron beam in current v.s. time ; cut-off sinusoidal current which is used in class B operation, I = I0 MAX(sinwt, 0).

Electron Gun

Cavity Design

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.

S-parameters of the RF resonator ; real (red) and imaginary (blue) values which shows us its cold frequency is 1.255GHz. (TM01-mode)

cathode area = 300cm2

Schematic Representation for Definition

ty

tx

T0

T00

; snapshot timetx ; transit timety ; departure timeT0 ; gap (d) transit time

= ty + tx

e-

e-

e-

e-

e-

e-

resonatorgrid 1

resonatorgrid 2

zd0

Schematic representation for the definition of snap shot time 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,

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.

SUMMARY