IPAC2011 - List of Authors (Pietralla, N.)

Paper	Title	Page
MOPC151	Design and Commissioning of a Multi-frequency Digital Low Level RF Control System*	433
	M. Konrad, U. Bonnes, C. Burandt, J. Conrad, R. Eichhorn, J. Enders, P.N. Nonn, N. Pietralla TU Darmstadt, Darmstadt, Germany
	Funding: Work supported by DFG through CRC 634 and by the BMBF under 06 DA 9024 I. Triggered by the need to control the superconducting cavities of the S-DALINAC, which have a high loaded quality factor and are thus very susceptible to microphonics, the development of a digital low level RF control system was started. The chosen design proved to be very flexible since other frequencies than the original 3 GHz may be adapted easily: The system converts the RF signal coming from the cavity (e. g. 3 GHz) down to the base band using a hardware I/Q demodulator. The base band signals are digitized by ADCs and fed into a FPGA where the control algorithm is implemented. The resulting signals are I/Q modulated before they are sent back to the cavity. The superconducting cavities are operated with a self-excited loop algorithm whereas a generator-driven algorithm is used for the low Q normal-conducting bunching cavities. A 6 GHz RF front end allows the synchronous operation of a new 2f buncher at the S-DALINAC. Meanwhile, a 325 MHz version has been built to control a pulsed prototype test stand for the p-LINAC at FAIR. We will present the architecture of the RF control system as well as results obtained during operation.

TUPC078	The Impact of the Duty Cycle on Gamma-particle Coincidence Measurements	1183
	P.R. John, J. Leske, N. Pietralla TU Darmstadt, Darmstadt, Germany
	Funding: Supported by BMBF under 06DA9041I Radioactive ion beam facilities deliver a great variety of different nuclei and thus open new possibilities for gamma-ray spectroscopy with radioactive isotopes. One of the challenges for the experimentalist is the high gamma background. To obtain nearly background-free spectra a gamma-particle coincidence measurement in inverse kinematics is well suited. Also for stable beams this method offers a lot of advantages. A crucial point for experimentalists for such kind of experiments is the duty cycle and the beam structure of the accelerator. For a typical set-up, the effect of the duty cycle and beam structure, e.g. resulting from different ion-sources, on data acquisition and thus the experiment will be shown from the experimentalist's point of view. The results will be discussed for selected accelerators, i.e. UNILAC (GSI, Germany), REX-ISOLDE (CERN, Switzerland) and ATLAS (ANL, USA).

WEPC006	Upgrade Plans on the Superconducting Electron Accelerator S-DALINAC	2010
	M. Kleinmann, R. Eichhorn, F. Hug, N. Pietralla TU Darmstadt, Darmstadt, Germany
	Funding: Work supported by DFG through SFB 634 The S-DALINAC is a superconducting recirculating electron accelerator with maximum design energy of 130 MeV operating in cw at 3 GHz. Even so the gradients of the superconducting cavities are well above design, their design quality factor of 3*10⁹ have not been reached so far, leading to higher heat transfer into the liquid helium than expected. Due to the limited cooling power of the cryo-plant being 120 W, the final energy achievable in cw operation is around 85 MeV, currently. In order to provide a cw beam with the designed final energy in the future, the installation of an additional recirculation path is projected. We will report on the beam-line and the magnet design for the new recirculation path. In addition, we will present the layout of two proposed scraper-systems which will be used to remove the halo of the electron beam allowing high precision coincidence experiments with very low background for nuclear physics in the future.

WEPC092	Moment-Based Simulation of the S-DALINAC Recirculations*	2223
	S. Franke, W. Ackermann, T. Weiland TEMF, TU Darmstadt, Darmstadt, Germany R. Eichhorn, F. Hug, C. Klose, N. Pietralla, M. Platz TU Darmstadt, Darmstadt, Germany
	Funding: Work supported by DFG under contract SFB 634. The Superconducting Linear Accelerator S-DALINAC installed at the institute of nuclear physics (IKP) at TU Darmstadt is designed as a re-circulating linear accelerator. The length of the beam line and the numerous accelerating structures as well as dipole and quadrupole magnets require a highly efficient numerical simulation tool in order to assist the operators by providing a detailed and almost instantaneous insight into the actual machine status. A suitable approach which enables a fast online calculation of the beam dynamics is given by the so-called moment approach where the particle distribution is represented by means of a discrete set of moments or by multiple discrete sets of moments in a multi-ensemble environment. Following this approach the V-Code simulation tool has been implemented at the Computational Electromagnetics Laboratory (TEMF) at TU Darmstadt. In this contribution an overview of the numerical model is presented together with new V-Code simulation results regarding the S-DALINAC recirculation sections.

Paper

Title

Page

Design and Commissioning of a Multi-frequency Digital Low Level RF Control System*

433

M. Konrad, U. Bonnes, C. Burandt, J. Conrad, R. Eichhorn, J. Enders, P.N. Nonn, N. Pietralla
TU Darmstadt, Darmstadt, Germany

Funding: Work supported by DFG through CRC 634 and by the BMBF under 06 DA 9024 I.
Triggered by the need to control the superconducting cavities of the S-DALINAC, which have a high loaded quality factor and are thus very susceptible to microphonics, the development of a digital low level RF control system was started. The chosen design proved to be very flexible since other frequencies than the original 3 GHz may be adapted easily: The system converts the RF signal coming from the cavity (e. g. 3 GHz) down to the base band using a hardware I/Q demodulator. The base band signals are digitized by ADCs and fed into a FPGA where the control algorithm is implemented. The resulting signals are I/Q modulated before they are sent back to the cavity. The superconducting cavities are operated with a self-excited loop algorithm whereas a generator-driven algorithm is used for the low Q normal-conducting bunching cavities. A 6 GHz RF front end allows the synchronous operation of a new 2f buncher at the S-DALINAC. Meanwhile, a 325 MHz version has been built to control a pulsed prototype test stand for the p-LINAC at FAIR. We will present the architecture of the RF control system as well as results obtained during operation.

TUPC078

The Impact of the Duty Cycle on Gamma-particle Coincidence Measurements

1183

P.R. John, J. Leske, N. Pietralla
TU Darmstadt, Darmstadt, Germany

Funding: Supported by BMBF under 06DA9041I
Radioactive ion beam facilities deliver a great variety of different nuclei and thus open new possibilities for gamma-ray spectroscopy with radioactive isotopes. One of the challenges for the experimentalist is the high gamma background. To obtain nearly background-free spectra a gamma-particle coincidence measurement in inverse kinematics is well suited. Also for stable beams this method offers a lot of advantages. A crucial point for experimentalists for such kind of experiments is the duty cycle and the beam structure of the accelerator. For a typical set-up, the effect of the duty cycle and beam structure, e.g. resulting from different ion-sources, on data acquisition and thus the experiment will be shown from the experimentalist's point of view. The results will be discussed for selected accelerators, i.e. UNILAC (GSI, Germany), REX-ISOLDE (CERN, Switzerland) and ATLAS (ANL, USA).

WEPC006

Upgrade Plans on the Superconducting Electron Accelerator S-DALINAC

2010

M. Kleinmann, R. Eichhorn, F. Hug, N. Pietralla
TU Darmstadt, Darmstadt, Germany

Funding: Work supported by DFG through SFB 634
The S-DALINAC is a superconducting recirculating electron accelerator with maximum design energy of 130 MeV operating in cw at 3 GHz. Even so the gradients of the superconducting cavities are well above design, their design quality factor of 3*10⁹ have not been reached so far, leading to higher heat transfer into the liquid helium than expected. Due to the limited cooling power of the cryo-plant being 120 W, the final energy achievable in cw operation is around 85 MeV, currently. In order to provide a cw beam with the designed final energy in the future, the installation of an additional recirculation path is projected. We will report on the beam-line and the magnet design for the new recirculation path. In addition, we will present the layout of two proposed scraper-systems which will be used to remove the halo of the electron beam allowing high precision coincidence experiments with very low background for nuclear physics in the future.

WEPC092

Moment-Based Simulation of the S-DALINAC Recirculations*

2223

S. Franke, W. Ackermann, T. Weiland
TEMF, TU Darmstadt, Darmstadt, Germany
R. Eichhorn, F. Hug, C. Klose, N. Pietralla, M. Platz
TU Darmstadt, Darmstadt, Germany

Funding: Work supported by DFG under contract SFB 634.
The Superconducting Linear Accelerator S-DALINAC installed at the institute of nuclear physics (IKP) at TU Darmstadt is designed as a re-circulating linear accelerator. The length of the beam line and the numerous accelerating structures as well as dipole and quadrupole magnets require a highly efficient numerical simulation tool in order to assist the operators by providing a detailed and almost instantaneous insight into the actual machine status. A suitable approach which enables a fast online calculation of the beam dynamics is given by the so-called moment approach where the particle distribution is represented by means of a discrete set of moments or by multiple discrete sets of moments in a multi-ensemble environment. Following this approach the V-Code simulation tool has been implemented at the Computational Electromagnetics Laboratory (TEMF) at TU Darmstadt. In this contribution an overview of the numerical model is presented together with new V-Code simulation results regarding the S-DALINAC recirculation sections.