Determination of coherent radiation

spectra from interferograms

Gennady Naumenko

Tomsk Polytechnic University

Contents

• Traditional interferometers Michelson interferometers Martin-Puplett interferometers

• Divided wave front (DWF) interferometer. Measurements in Tomsk Polytechnic University Test in Shanghai Institute of Applied Physics • Possibility for spectral measurement on LUCX

Coherent synchrotron radiation spectra measurement on the FLASH beam

FLASH experimental conditions

• Single bunch charge: 0.6-0.9 nCb (4109e-)

• Single bunch length: 100 fsec

• Radiation energy from single bunch 50-100 nJ

• Lorenz-factor: 300

• A train consists of 1-100 single bunches

G. Naumenko, A. Potylitsyn, G. Kube, O. Grimm, V. Cha, Yu. Popov. NIM A 603 (2009) 35-37

DPU-1

Martin-Puplett interferometer of DESY TOSYLAB

The time characteristics of detector allow us to measure radiation from choosed separate bunch in train.

Detector DPU-1

(Tomsk Semi Conductive Devices Institute )

Low threshold diode Broadband

antenna

Spectrum reconstruction(Fourier transformation of interferogram)

DPU-1 Detector Sygnal Amplitudes

roof mirror position (mm)

79.0 79.5 80.0 80.5 81.0 81.5

det

ecto

r vo

ltag

e (V

)

0.00

0.01

0.02

0.03

0.04Sample of interferogram

of DESY TOSYLAB CSR beam

Lars Froehlich. DESY-THESIS 2005-011, FEL-THESIS 2005-02J

Divided wave front (DWF) interferometer. G. Naumenko, A. Potylitsyn, M. Shevelev, Yu. Popov, L. Sukhikh. Russian Physical Journal. 11 2 (2009) 254G. Naumenko, A. Potylitsyn, M. Shevelev , V. Soboleva, V. Bleko. IFOST-2012 proceedings (to be published)

R ad ia tio n

M o v ab le

Mir

rors

D e te c to r

F o cu s

R ad ia to rM o v ab le m irro r

D e te c to r

DWF interferometer for Tomsk microtron conditions

3 20mm

Sample from radiation source with wavelength 11.6 mm

Interferogram

Spectrum reconstructed

Mirror position (mm)

-100 -50 0 50 100

Rad

iati

on y

ield

(ar

b. u

n.)

0

500

1000

Wavelength (mm)

0 10 20 30 40

Ra

dia

tion

yie

ld (

arb

. u

n.)

0

10000

20000

30000

40000

The spectral resolution depends on the quality of plane and parabolic mirrors and on the aperture of detector. For this case the spectral resolution was

The spectrum reconstruction procedure is similar to the previous one.

6%

Sample of Tomsk microtron pseudo-photon spectrum

measurement

Mirror position (mm)

-100 -50 0 50 100

Rad

iati

on y

ield

(ar

b. u

n.)

0

500

1000

1500

2000

2500

3000

3500

Wavelength (mm)

0 10 20 30 40

Ra

dia

tion

yie

ld (

arb

. u

n.)

0

2e+4

4e+4

6e+4

8e+4

1e+5

B u n ch fie ld

E lectron b eam

Interferogram

Spectrum reconstructed

6.2

2.3

Electron energy MeV

Bunch length mm

Mirror position (mm)

-100 -50 0 50 100

Rad

iati

on y

ield

(ar

b. u

n.)

200

300

400

500

CChR spectrum measurement

Interfer

ometer

Interferogram

Spectrum

B e 20m h

Teflon target

CC

hR

Wavelength (mm)

0 10 20 30 40

Ra

dia

tion

yie

ld (

arb

. u

n.)

0

2000

4000

6000

8000

10000

12000

Test in Shanghai Institute of Applied Physics

20

0.19

Electron energy MeV

Bunch length mm

Zhang J.B., Shkitov D.A., Lu S.L., Shevelev M.V., Yu T.M., Potylitsyn A.P.,Ye K.R., Naumenko G.A., Deng H.X.

Proceedings IBIC-12 (to be published)

SPI-D Broadband Pyroelectric THz

Radiometer

DWF interferometer

or TR target

CTR spectrum measurement using Michelson interferometer

f (GHz)

0 100 200 300 400 500 600 700 800 900

Y D

ata

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

Interferogram

Spectrum

f (GHz)

0 100 200 300 400 500

Yie

ld (

arb.

un.

)

0

2

4

6

8

10

12

14

16

Pseudo-photon spectrum measurement using DWF interferometer

Mirror position (mm)

55 60 65 70 75 80

Yie

ld (

arb.

un.

)

2.5

3.0

3.5

4.0

4.5Interferogram from DWF interferometer

SpectrumThe same scheme was used, but the mirror of Michelson interferometer was installed in the center of interferogram.

e-

Possibility for spectral measurement on LUCX

For bunch length= 10 ps we may have a coherent radiation in millimeter wavelength region. So the DWF interferometer with parameters used in Tomsk may be applicable for LUCX.

Michelson interferometerMin. Order: 1 SetFOB Price: US $3500/ Set

The DWF interferometer approximately two times cheaper. In addition, this interferometer provides the possibility to measure not only real photon spectra, but also the spectra of pseudo-

photons.