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A Laser-Based Beam Density Distribution Diagnostic for the RAL Front End Test Stand David Lee

Outline The RAL Front End Test Stand The Need for Non-Destructive, Non-Interceptive Diagnostics Laser-Based H − Beam Diagnostics: Basic Principle The Approach Taken Progress Made: Particle Transport Simulations Laser Characterisation Conclusions and Outlook A Laser- Based Beam Density Distribution Diagnostic for the RAL Front End Test Stand • 1 David Lee • 02/04/2007

The Front End Test Stand MEBT and chopper RFQ Magnetic LEBT H- ion source Laser profile monitor A Laser- Based Beam Density Distribution Diagnostic for the RAL Front End Test Stand • 2 David Lee • 02/04/2007

The Front End Test Stand MEBT and chopper RFQ Magnetic LEBT H- ion source Laser profile monitor A Laser- Based Beam Density Distribution Diagnostic for the RAL Front End Test Stand • 3 David Lee • 02/04/2007

The Need for Non-Destructive, Non-Interceptive Diagnostics Allows for online monitoring of the beam A Laser- Based Beam Density Distribution Diagnostic for the RAL Front End Test Stand • 4 David Lee • 02/04/2007

The Need for Non-Destructive, Non-Interceptive Diagnostics Allows for online monitoring of the beam Prevents the beam damaging the instrument P46 Plastic Ruby A Laser- Based Beam Density Distribution Diagnostic for the RAL Front End Test Stand • 5 David Lee • 02/04/2007

Laser-based Beam Diagnostics: Principle for H − Collect the detached electrons − − − − − − − − − − − − − − − − − − − − − − − − − − − − − − Photo-dissociate some Separate species using a of the H - ions dipole magnet A Laser- Based Beam Density Distribution Diagnostic for the RAL Front End Test Stand • 6 David Lee • 02/04/2007

Laser-based Beam Diagnostics: Principle for H − Collect the detached electrons − − − − − − − − − − − − − − − − − − − − − − − − − − − − − − Photo-dissociate some Separate species using a of the H - ions dipole magnet A Laser- Based Beam Density Distribution Diagnostic for the RAL Front End Test Stand • 7 David Lee • 02/04/2007

Laser-based Beam Diagnostics: Principle for H − Collect the detached electrons − − − − − − − − − − − − − − − − − − − − − − − − − − − − − − Photo-dissociate some Separate species using a of the H - ions dipole magnet A Laser- Based Beam Density Distribution Diagnostic for the RAL Front End Test Stand • 8 David Lee • 02/04/2007

Laser-based Beam Diagnostics: Principle for H − Collect the detached electrons − − − − − − − − − − − − − − − − − − − − − − − − − − − − − − Photo-dissociate some Separate species using a of the H - ions dipole magnet A Laser- Based Beam Density Distribution Diagnostic for the RAL Front End Test Stand • 9 David Lee • 02/04/2007

Laser-based Beam Diagnostics: Principle for H − Collect the detached electrons − − − − − − − − − − − − − − − − − − − − − − − − − − − − − − Photo-dissociate some Separate species using a of the H - ions dipole magnet A Laser- Based Beam Density Distribution Diagnostic for the RAL Front End Test Stand • 10 David Lee • 02/04/2007

The Need for Multiple (>2) Projections A Laser- Based Beam Density Distribution Diagnostic for the RAL Front End Test Stand • 11 David Lee • 02/04/2007

The Need for Multiple (>2) Projections A Laser- Based Beam Density Distribution Diagnostic for the RAL Front End Test Stand • 12 David Lee • 02/04/2007

The Need for Multiple (>2) Projections A Laser- Based Beam Density Distribution Diagnostic for the RAL Front End Test Stand • 13 David Lee • 02/04/2007

The Need for Multiple (>2) Projections A Laser- Based Beam Density Distribution Diagnostic for the RAL Front End Test Stand • 14 David Lee • 02/04/2007

The Need for Multiple (>2) Projections A Laser- Based Beam Density Distribution Diagnostic for the RAL Front End Test Stand • 15 David Lee • 02/04/2007

The Need for Multiple (>2) Projections A Laser- Based Beam Density Distribution Diagnostic for the RAL Front End Test Stand • 16 David Lee • 02/04/2007

The Need for Multiple (>2) Projections A Laser- Based Beam Density Distribution Diagnostic for the RAL Front End Test Stand • 17 David Lee • 02/04/2007

Simulated Detector Performance A Laser- Based Beam Density Distribution Diagnostic for the RAL Front End Test Stand • 18 David Lee • 02/04/2007

Simulated Detector Performance A Laser- Based Beam Density Distribution Diagnostic for the RAL Front End Test Stand • 19 David Lee • 02/04/2007

Laser Characterisation A Laser- Based Beam Density Distribution Diagnostic for the RAL Front End Test Stand • 20 David Lee • 02/04/2007

Laser Characterisation Maximum ion beam size 2.6% change in spot size at edge of ion beam 1 mm at focus A Laser- Based Beam Density Distribution Diagnostic for the RAL Front End Test Stand • 21 David Lee • 02/04/2007

Conclusions and Outlook Non-destructive diagnostics are essential for high-power ion beams Laser-based diagnostics are a solution Progress towards installation and operation of a laser-based beam density distribution diagnostic for the RAL Front End Test Stand is going well Electromagnetic simulations show efficient electron collection Laser characterisation shows that a good resolution can be reached Installation and first measurements are on schedule for the summer A Laser- Based Beam Density Distribution Diagnostic for the RAL Front End Test Stand • 22 David Lee • 02/04/2007

Spare slides

Abstract The RAL Front End Test Stand is being constructed to demonstrate the production of a 60 mA, 3 MeV, 50 pps, chopped H- beam suitable for future high-power proton accelerators. Due to the high beam brightness and a desire to have online instrumentation while the accelerator is operational, a series of non- intrusive, non-destructive diagnostics, based on the photo-detachment of the outer electrons of the H- ions, are being developed. This talk describes a device that will measure the 2D ion beam density distribution, due to be installed in the summer. A Laser- Based Beam Density Distribution Diagnostic for the RAL Front End Test Stand • 24 David Lee • 02/04/2007

H − Injection H − from Linac Stripping foil Circulating protons A Laser- Based Beam Density Distribution Diagnostic for the RAL Front End Test Stand • 25 David Lee • 02/04/2007

Laser-based beam diagnostics principle for H − Rev. Sci. Instrum. 73 , 998 (2002) Collect the detached electrons − − − − − − − − − − − − − − − − − − − − − − − − − − − − − − Photo-dissociate some Separate species using a of the H - ions dipole magnet A Laser- Based Beam Density Distribution Diagnostic for the RAL Front End Test Stand • 26 David Lee • 02/04/2007

ADC Two channel, integrate and hold, 20-bit ADC Minimum sensitivity: −0.2– 50 pC Expected signal size ~1 pC so in effect we have a ~ 14-bit ADC A Laser- Based Beam Density Distribution Diagnostic for the RAL Front End Test Stand • 27 David Lee • 02/04/2007

ADC Protoboard RS232 to PC Atmel μ processor Power in Range select jumpers DDC112 Input 1 Clock In A Laser- Based Beam Density Distribution Diagnostic for the RAL Front End Test Stand • 28 David Lee • 02/04/2007

ADC Test Charge Resolution A Laser- Based Beam Density Distribution Diagnostic for the RAL Front End Test Stand • 29 David Lee • 02/04/2007