IPAC2011 - List of Authors (Heid, O.)

Paper	Title	Page
MOPC129	Compact Solid State RF-Modules for Direct Drive RF-linacs	382
	R. Irsigler, M. Back, R. Baumgartner, O. Heid, T.J.S. Hughes, M. Kaspar, T. Kluge, J. Sirtl, K. Weidner, M. Zerb Siemens AG, München, Germany
	We present a modular RF power source concept based on solid state RF-modules with novel SiC transistors. The concept offers lower cost, better reliability and reduced maintenance compared to traditional RF-source technology. No circulators are required, which makes the RF-module very compact and reliable. The SiC power transistor has a very low input capacitance and was optimized for low gate resistance to enable fast switching in the VHF range. It delivers a maximum pulsed drain saturation current of 65 A. The transistor provides at 350 V supply voltage and 150 MHz an output power of 5,6 kW at a gain of 15,8 dB. It is essential to avoid high parasitic source inductances at RF and good thermal conductivity is required for operation at high duty cycle. We have built very compact 75 x 90 mm ceramic amplifier modules using a planar interconnect technology (SIPLIT) to connect the bare die transistors to the DCB substrate. The modules have a fully symmetric push-pull topology (circlotron) with four transistors in parallel in each leg. The RF-modules delivered at 150 MHz an impressive RF output power in the range of 40 kW. Further tests at 324 MHz are planned and will be presented.

TUPS080	Low Energy Bunching with a Double Gap RF Buncher	1725
	H. von Jagwitz, U. Hagen, O. Heid, S. Setzer Siemens AG, Erlangen, Germany
	A compact double gap bunching system for low energy proton beams is presented. The system is designed for the bunching of a low current proton beam (less than 50μA) with an energy of 10 keV. The buncher operates at 150 MHz and bunches without significantly changing the beam energy. The beam is generated by an Electron Beam Ion Source and has to be bunched for the subsequent acceleration in a 150 MHz linear accelerator. The buncher contains two short gaps and an RF electrode inbetween. Thus the full length of the buncher in the beamline is in the range of 2 cm. The location of the bunch focus depends on the buncher power. The bunched beam was analysed at a distance of 550 mm with a fast faraday cup. The bunching effectivity was determined as 50%, which means that 50% of the protons of the beam were located in bunches with a width of 60°, which is a reasonable value of acceptance for a conventional accelerator cavity. Some theory and detailed results will be presented.

TUPS077	Shaping of Ion Pulses from an Electron Beam Ion Source for Particle Injection into Accelerators	1716
	F. Ullmann, A. Schwan DREEBIT GmbH, Dresden, Germany U. Hagen, O. Heid, H. von Jagwitz Siemens AG, Healthcare Technology and Concepts, Erlangen, Germany G. Zschornack Technische Universität Dresden, Institut für Angewandte Physik, Dresden, Germany
	Electron Beam Ion Sources (EBISs) provide highly charged ions for many applications, amongst others for particle injection into accelerators. Although EBISs are limited in ion output they feature a lot of advantages which qualify them for accelerator injection. The ion pulses extracted from the ion sources can be directly injected into an accelerator sequence which however requires ion pulses with distinct shape and length. We present the production of ion pulses matching the requirements of particle injection. The ions are produced by trapping in a high density electron beam for a certain time with electrostatic potentials providing for their axial trapping. The ions are extracted by lowering the trapping potential, i.e. opening the trap. Due to the ion energy distribution within the trapping region ion extraction can be controlled by controlling the trapping potential. A specific time dependent control mode of the trapping potential thus allows to produce ion pulses with designated shape and length. Source parameters such as working gas pressure, electron beam current and energy are influencing the energy distribution of the ions which in turn is influencing pulse shaping.

TUPS079	Construction of a Novel Compact High Voltage Electrostatic Accelerator	1722
	P. Beasley, O. Heid Siemens AG, Healthcare Technology and Concepts, Erlangen, Germany
	A compact demonstrator system based on a Cockcroft-Walton (or Greinacher) cascade has been successfully built and tested. The concept has been developed using modern materials and a different design philosophy, which in turn can then enable this novel configuration to operate at much higher voltage gradients. This paper explores the progress made over the past 18 months and future plans to utilise the technology to develop one such concept for an energy efficient 10MV, 100μA, tandem proton accelerator, with a <2m2 footprint. The development of such a compact high voltage particle accelerator, with high current capability has the potential to access a wide range of commercial opportunities outside the laboratory.

Paper

Title

Page

Compact Solid State RF-Modules for Direct Drive RF-linacs

382

R. Irsigler, M. Back, R. Baumgartner, O. Heid, T.J.S. Hughes, M. Kaspar, T. Kluge, J. Sirtl, K. Weidner, M. Zerb
Siemens AG, München, Germany

We present a modular RF power source concept based on solid state RF-modules with novel SiC transistors. The concept offers lower cost, better reliability and reduced maintenance compared to traditional RF-source technology. No circulators are required, which makes the RF-module very compact and reliable. The SiC power transistor has a very low input capacitance and was optimized for low gate resistance to enable fast switching in the VHF range. It delivers a maximum pulsed drain saturation current of 65 A. The transistor provides at 350 V supply voltage and 150 MHz an output power of 5,6 kW at a gain of 15,8 dB. It is essential to avoid high parasitic source inductances at RF and good thermal conductivity is required for operation at high duty cycle. We have built very compact 75 x 90 mm ceramic amplifier modules using a planar interconnect technology (SIPLIT) to connect the bare die transistors to the DCB substrate. The modules have a fully symmetric push-pull topology (circlotron) with four transistors in parallel in each leg. The RF-modules delivered at 150 MHz an impressive RF output power in the range of 40 kW. Further tests at 324 MHz are planned and will be presented.

TUPS080

Low Energy Bunching with a Double Gap RF Buncher

1725

H. von Jagwitz, U. Hagen, O. Heid, S. Setzer
Siemens AG, Erlangen, Germany

A compact double gap bunching system for low energy proton beams is presented. The system is designed for the bunching of a low current proton beam (less than 50μA) with an energy of 10 keV. The buncher operates at 150 MHz and bunches without significantly changing the beam energy. The beam is generated by an Electron Beam Ion Source and has to be bunched for the subsequent acceleration in a 150 MHz linear accelerator. The buncher contains two short gaps and an RF electrode inbetween. Thus the full length of the buncher in the beamline is in the range of 2 cm. The location of the bunch focus depends on the buncher power. The bunched beam was analysed at a distance of 550 mm with a fast faraday cup. The bunching effectivity was determined as 50%, which means that 50% of the protons of the beam were located in bunches with a width of 60°, which is a reasonable value of acceptance for a conventional accelerator cavity. Some theory and detailed results will be presented.

TUPS077

Shaping of Ion Pulses from an Electron Beam Ion Source for Particle Injection into Accelerators

1716

F. Ullmann, A. Schwan
DREEBIT GmbH, Dresden, Germany
U. Hagen, O. Heid, H. von Jagwitz
Siemens AG, Healthcare Technology and Concepts, Erlangen, Germany
G. Zschornack
Technische Universität Dresden, Institut für Angewandte Physik, Dresden, Germany

Electron Beam Ion Sources (EBISs) provide highly charged ions for many applications, amongst others for particle injection into accelerators. Although EBISs are limited in ion output they feature a lot of advantages which qualify them for accelerator injection. The ion pulses extracted from the ion sources can be directly injected into an accelerator sequence which however requires ion pulses with distinct shape and length. We present the production of ion pulses matching the requirements of particle injection. The ions are produced by trapping in a high density electron beam for a certain time with electrostatic potentials providing for their axial trapping. The ions are extracted by lowering the trapping potential, i.e. opening the trap. Due to the ion energy distribution within the trapping region ion extraction can be controlled by controlling the trapping potential. A specific time dependent control mode of the trapping potential thus allows to produce ion pulses with designated shape and length. Source parameters such as working gas pressure, electron beam current and energy are influencing the energy distribution of the ions which in turn is influencing pulse shaping.

TUPS079

Construction of a Novel Compact High Voltage Electrostatic Accelerator

1722

P. Beasley, O. Heid
Siemens AG, Healthcare Technology and Concepts, Erlangen, Germany

A compact demonstrator system based on a Cockcroft-Walton (or Greinacher) cascade has been successfully built and tested. The concept has been developed using modern materials and a different design philosophy, which in turn can then enable this novel configuration to operate at much higher voltage gradients. This paper explores the progress made over the past 18 months and future plans to utilise the technology to develop one such concept for an energy efficient 10MV, 100μA, tandem proton accelerator, with a <2m2 footprint. The development of such a compact high voltage particle accelerator, with high current capability has the potential to access a wide range of commercial opportunities outside the laboratory.