NON-DESTRUCTIVE SINGLE PASS MONITOR OF

LONGITUDINAL CHARGE DISTRIBUTION

P.V.Logatchov, P.A.Bak, E.A.Gousev, A.A.Starostenko, N.S.Dikansky,

M.V.Korabelnikov, S.V.Shiyankov, BINP, Novosibirsk, Russia

Contact e-mail: logatchov@inp.nsk.su

Z

Y

X

0

Linear

scattering

22 )(

)()(2)(

zx

dzznzxrx e

z

22 )(

)(2)(

zx

dzznrx e

y

dzznNe )(

dllqI

cx

B

A

<<1.

for

1. >>1,

2. max y

Single pass beam monitor is sutable tool for:

1. Longitudinal charge distribution2. Beam trains transverse distribution3. Wake-fields observation after the bunch

The longitudinal distribution of charge density in an bunch:

-10 ..- 60 kV, 5mks

Faraday cup

0..- 800 V, 30 ns

+6.2 kV, 60 ns1.2 GeV bunch

Testing beamCathode MCP Luminophore

CCD

Synchronization system

Videograbber

Electron gunmodulator

MCPmodulator

Luminophoremodulator

LensCorrector

Electron gun

Scheme of LCDM

The bunch parameters range for better then 10% time resolution of this method:

• bunch peak current: 10 A - 250 A

• bunch length: 20 ps - 2000 ps

• gamma factor: > 30

• offset parameres: < 1/6 of bunch length

Single bunch regime

Single bunch regime: offset parameter goes downSingle bunch regime: offset parameter goes down

11

33

22

44

Collision with the single bunch

Single bunch regime: offset parameter goes down

Multi bunch regime: offset parameter goes down1-4: offset parameter > 05 : offset parameter 06-8: offset parameter < 0

88765

4321

Pictures with wakes

Collision with single bunchTwo bunches

Wakes start to appear

330 ps

Wake fields 10 ns after bunch

Wake fields150 ns after bunch

The bunch with starting wakes

330 psDifferent vert. probe beam position

• Observation of the wake fields corresponded to the frequency of 8714 MHz