The PITZ Plasma Source

Matthias Gross

LAOLA Workshop

Wismar, 24. June 2015

WG1 – Plasma targets, diagnostics and plasma beam transport

Matthias Gross | LAOLA workshop | 24. June 2015 | Page 2

Beam Line Remodeling

Electron

Beam

Plasma cell

Ionization laser

Dipole

Quad 1…4

Quad 5…6

Quad 7…8

Matthias Gross | LAOLA workshop | 24. June 2015 | Page 3

Plasma Cell Design

Thermal

Insulation Cooling

Sleeve

Electron

Window

Helium

Distribution

Heating Coils

e-

Ionization

Laser Path Laser

Window

Design:

Gerald Koss

Matthias Gross | LAOLA workshop | 24. June 2015 | Page 4

> ASTRA simulations: electron beam scattering impedes focusing into the

plasma

> Maximal agreeable scattering angle: 0.2 mrad

> 8m Kapton foil for first experiments expect 1 mrad

Scattering at Electron Window

Strongly defocused

0.4 mrad

Window position Middle of plasma cell

Focus still ok –

can be optimized

0.2 mrad

Matthias Gross | LAOLA workshop | 24. June 2015 | Page 5

Pre-experiment #1: Screen station

> Purpose: Find quadrupole settings for best focusing

> Best result: <100m spot size (100 pC bunch charge; 22 MeV; no

scattering foil)

e-

Screen

Station

Camera

Matthias Gross | LAOLA workshop | 24. June 2015 | Page 6

> Purpose: test of interaction electron beam electron window foils

Pre-experiment #2: Dummy Plasma Cell

e-

Electron

windows:

8m Kapton

Gas inlet

(1mbar Ar)

Matthias Gross | LAOLA workshop | 24. June 2015 | Page 7

> Purpose: test of interaction electron beam electron window foils

> Capturing of tightly focused beam behind plasma cell (at that time only

2 Quads available for beam capturing)

Pre-experiment #2: Dummy Plasma Cell

Matthias Gross | LAOLA workshop | 24. June 2015 | Page 8

Summary

> PITZ beamline was remodeled for plasma experiments

> Several preparatory experiments have been performed

1) Beam dynamics: <100m focusing into plasma cell was achieved

2) Electron beam – plasma cell interaction: 8m Kapton foil could be used for first

experiments

> Simulation shows strong scattering, but beam passed plasma cell intact

Matthias Gross | LAOLA workshop | 24. June 2015 | Page 9

Backup

Matthias Gross | LAOLA workshop | 24. June 2015 | Page 10

> Purpose: Find maximal allowable window foil thickness

> Result: 3m (to be checked: gas diffusion)

Pre-experiment #3: Electron Beam Scattering

0.1 1 10

0.01

0.1

1

10

Simulation (FLUKA)

Equation (Multiple Coulomb scattering)

Experiment in PITZ beam line

Div

erg

en

ce

(m

rad

)

Foil thickness (µm)

Goal: 0.2 mrad