IBIC2013 - List of Keywords (resonance)

Paper	Title	Other Keywords	Page
MOPF23	Quantifying Dissipated Power From Wake Field Losses in Diagnostics Structures	simulation, impedance, single-bunch, DIAMOND	259
	A.F.D. Morgan, G. Rehm Diamond, Oxfordshire, United Kingdom
	As a charged particle beam passes through structures, wake fields can deposit a fraction of the energy carried by the beam as characterised by the wake loss factor. Some part of the deposited energy will be emitted into the beam pipe, some part can be coupled out of signal ports and some part will be absorbed by the materials of the structures. With increasingly higher stored currents, we require a better understanding of where all the energy deposited by wake losses ends up in order to avoid damaging components. This is of particular concern for diagnostics structures as they are often designed to couple a small fraction of energy from the beam, which makes them susceptible to thermal damage due to increased localised losses. We will detail the simulation and analysis approach which we have developed to quantify power deposition within structures. As an example the analysis of a beam position monitor pickup block of the Diamond storage ring is shown.
	Poster MOPF23 [0.249 MB]

TUPF34	Resonant TE Wave Measurement of Electron Cloud Density Using Multiple Sidebands	simulation, electron, positron, pick-up	597
	J.P. Sikora, J.A. Crittenden Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA S. De Santis LBNL, Berkeley, California, USA A.J. Tencate ISU, Pocatello, Idaho, USA
	Funding: This work is supported by the US National Science Foundation PHY-0734867, PHY-1002467, and the US Department of Energy DE-FC02-08ER41538, DE-SC0006505. A change in electron cloud (EC) density will change the resonant frequency of a section of beam-pipe. With a fixed drive frequency, the resulting dynamic phase shift across the resonant section will include the convolution of the frequency shift with the impulse response of the resonance. The effect of the convolution on the calculated modulation sidebands is in agreement with measured data, including the absolute value of the EC density obtained from ECLOUD simulations. These measurements were made at the Cornell Electron Storage Ring (CESR) which has been reconfigured as a test accelerator (CesrTA) with positron or electron beam energies ranging from 2 GeV to 5 GeV.
	Poster TUPF34 [2.423 MB]

TUPF35	Resonant TE Wave Measurement of Electron Cloud Density Using Phase Detection	positron, electron, storage-ring, damping	601
	J.P. Sikora Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA S. De Santis LBNL, Berkeley, California, USA
	Funding: This work is supported by the US National Science Foundation PHY-0734867, PHY-1002467, and the US Department of Energy DE-FC02-08ER41538, DE-SC0006505. The resonant TE wave technique can use modulation sidebands for the calculation of electron cloud (EC) density. An alternative is to mix the drive and received signals to form a phase detector. Using this technique, the phase shift across the resonant section of beam-pipe can be observed directly on an oscilloscope. The growth and decay of the EC density has a time constant of roughly 100 ns, while the measured phase shift will include a convolution of the EC density with the impulse response of the resonant beam-pipe - typically about 500 ns. So any estimate of the growth/decay of the cloud requires deconvolution of the measured signal with the response time of the resonance. We have also used this technique to look for evidence of EC density with a lifetime that is long compare to the revolution period of the stored beam. These measurements were made at the Cornell Electron Storage Ring (CESR) which has been reconfigured as a test accelerator (CesrTA) with positron or electron beam energies ranging from 2 GeV to 5 GeV.
	Poster TUPF35 [2.554 MB]

TUPF36	Analysis of Modulation Signals Generated in the TE Wave Detection Method For Electron Cloud Measurements	electron, vacuum, BPM, pick-up	605
	S. De Santis LBNL, Berkeley, California, USA J.P. Sikora Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
	Funding: Work supported by the U.S. Department of Energy and by the US National Science Foundation under Contracts No. DE-AC02-05CH11231, DE-FC02-08ER41538, DE-SC0006505, PHY-0734867, PHY-1002467. The evaluation of the electron cloud density in storage rings by measuring its effects on the transmission of electromagnetic signals across portions of the beampipe is a widely used technique and the most suited for measurements over extended regions. Recent results show that in a majority of cases the RF signal transmission takes place by coupling to standing waves excited in the vacuum chamber. In such a case the effect of a varying cloud density is a simultaneous amplitude, phase and frequency modulation of a fixed frequency drive signal. The characteristics of the modulation depend not only on the cloud density values and spatial distribution, but also on its temporal evolution and on the damping time of the standing waves. In this paper we evaluate the relationship between measured modulation sidebands amplitude and the electron cloud density when cloud and electromagnetic resonance rise and fall times are of the same order of magnitude, as it is the case in the accelerators where we have conducted our experiments.

WEPC40	Pickup Signal Improvement for High Bandwidth BAMs for FLASH and European - XFEL	pick-up, simulation, DESY, laser	778
	A. Angelovski, R. Jakoby, A. Penirschke TU Darmstadt, Darmstadt, Germany M.K. Czwalinna, H. Schlarb, C. Sydlo DESY, Hamburg, Germany T. Weiland TEMF, TU Darmstadt, Darmstadt, Germany
	In order to measure the arrival time of the electron bunches in low (20 pC) and high (1 nC) charge operation mode, new high bandwidth pickups were developed as a part of the Bunch Arrival-time Monitors (BAMs) for FLASH at DESY . The pickup signal is transported via radiation resistant coaxial cables to the electro-optic modulator (EOM) . Due to the high losses of the 40 GHz RF front-end the signal in the RF path is attenuated well below the optimal operation voltage of the EOM. To improve the overall performance, the signal strength of the induced pickup signal needs to be increased and at the same time the losses in the RF front-end significantly reduced. In this paper, the analysis towards improving the induced pickup signal strength is presented. Simulations are performed with the CST STUDIO SUITE package and the results are compared with the state of the art high bandwidth pickups. A. Angelovski et al., Phys. Rev. ST Accel. Beams 15, 112803 (2012) ** A. Penirschke et al., Proc. of IBIC2012, Tsukuba, Japan (2012)

THBL1	RF Heating from Wake Losses in Diagnostics Structures	longitudinal, LHC, impedance, simulation	929
	E. Métral CERN, Geneva, Switzerland
	Heating of diagnostics structures (striplines, buttons, screen vessels, wire scanners etc) has been observed at many facilities with higher stored currents. Simulations of wake losses using 3D EM codes are regularly used to estimate the amount of power lost from the bunched beam but on its own this does not tell how much is radiated back into the beam pipe or transmitted into external ports and how much is actually being dissipated in the structure and where. This talk should introduce into the matter, summarise some of the observations at various facilities and illustrate what approaches of detailed simulations have been taken. summarizing a workshop at DLS (see http://tinyurl.com/wakeloss )
	Slides THBL1 [9.078 MB]

Paper

Title

Other Keywords

Page

MOPF23

Quantifying Dissipated Power From Wake Field Losses in Diagnostics Structures

simulation, impedance, single-bunch, DIAMOND

259

A.F.D. Morgan, G. Rehm
Diamond, Oxfordshire, United Kingdom

As a charged particle beam passes through structures, wake fields can deposit a fraction of the energy carried by the beam as characterised by the wake loss factor. Some part of the deposited energy will be emitted into the beam pipe, some part can be coupled out of signal ports and some part will be absorbed by the materials of the structures. With increasingly higher stored currents, we require a better understanding of where all the energy deposited by wake losses ends up in order to avoid damaging components. This is of particular concern for diagnostics structures as they are often designed to couple a small fraction of energy from the beam, which makes them susceptible to thermal damage due to increased localised losses. We will detail the simulation and analysis approach which we have developed to quantify power deposition within structures. As an example the analysis of a beam position monitor pickup block of the Diamond storage ring is shown.

Poster MOPF23 [0.249 MB]

TUPF34

Resonant TE Wave Measurement of Electron Cloud Density Using Multiple Sidebands

simulation, electron, positron, pick-up

597

J.P. Sikora, J.A. Crittenden
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
S. De Santis
LBNL, Berkeley, California, USA
A.J. Tencate
ISU, Pocatello, Idaho, USA

Funding: This work is supported by the US National Science Foundation PHY-0734867, PHY-1002467, and the US Department of Energy DE-FC02-08ER41538, DE-SC0006505.
A change in electron cloud (EC) density will change the resonant frequency of a section of beam-pipe. With a fixed drive frequency, the resulting dynamic phase shift across the resonant section will include the convolution of the frequency shift with the impulse response of the resonance. The effect of the convolution on the calculated modulation sidebands is in agreement with measured data, including the absolute value of the EC density obtained from ECLOUD simulations. These measurements were made at the Cornell Electron Storage Ring (CESR) which has been reconfigured as a test accelerator (CesrTA) with positron or electron beam energies ranging from 2 GeV to 5 GeV.

Poster TUPF34 [2.423 MB]

TUPF35

Resonant TE Wave Measurement of Electron Cloud Density Using Phase Detection

positron, electron, storage-ring, damping

601

J.P. Sikora
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
S. De Santis
LBNL, Berkeley, California, USA

Funding: This work is supported by the US National Science Foundation PHY-0734867, PHY-1002467, and the US Department of Energy DE-FC02-08ER41538, DE-SC0006505.
The resonant TE wave technique can use modulation sidebands for the calculation of electron cloud (EC) density. An alternative is to mix the drive and received signals to form a phase detector. Using this technique, the phase shift across the resonant section of beam-pipe can be observed directly on an oscilloscope. The growth and decay of the EC density has a time constant of roughly 100 ns, while the measured phase shift will include a convolution of the EC density with the impulse response of the resonant beam-pipe - typically about 500 ns. So any estimate of the growth/decay of the cloud requires deconvolution of the measured signal with the response time of the resonance. We have also used this technique to look for evidence of EC density with a lifetime that is long compare to the revolution period of the stored beam. These measurements were made at the Cornell Electron Storage Ring (CESR) which has been reconfigured as a test accelerator (CesrTA) with positron or electron beam energies ranging from 2 GeV to 5 GeV.

Poster TUPF35 [2.554 MB]

TUPF36

Analysis of Modulation Signals Generated in the TE Wave Detection Method For Electron Cloud Measurements

electron, vacuum, BPM, pick-up

605

S. De Santis
LBNL, Berkeley, California, USA
J.P. Sikora
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

Funding: Work supported by the U.S. Department of Energy and by the US National Science Foundation under Contracts No. DE-AC02-05CH11231, DE-FC02-08ER41538, DE-SC0006505, PHY-0734867, PHY-1002467.
The evaluation of the electron cloud density in storage rings by measuring its effects on the transmission of electromagnetic signals across portions of the beampipe is a widely used technique and the most suited for measurements over extended regions. Recent results show that in a majority of cases the RF signal transmission takes place by coupling to standing waves excited in the vacuum chamber. In such a case the effect of a varying cloud density is a simultaneous amplitude, phase and frequency modulation of a fixed frequency drive signal. The characteristics of the modulation depend not only on the cloud density values and spatial distribution, but also on its temporal evolution and on the damping time of the standing waves. In this paper we evaluate the relationship between measured modulation sidebands amplitude and the electron cloud density when cloud and electromagnetic resonance rise and fall times are of the same order of magnitude, as it is the case in the accelerators where we have conducted our experiments.

WEPC40

Pickup Signal Improvement for High Bandwidth BAMs for FLASH and European - XFEL

pick-up, simulation, DESY, laser

778

A. Angelovski, R. Jakoby, A. Penirschke
TU Darmstadt, Darmstadt, Germany
M.K. Czwalinna, H. Schlarb, C. Sydlo
DESY, Hamburg, Germany
T. Weiland
TEMF, TU Darmstadt, Darmstadt, Germany

In order to measure the arrival time of the electron bunches in low (20 pC) and high (1 nC) charge operation mode, new high bandwidth pickups were developed as a part of the Bunch Arrival-time Monitors (BAMs) for FLASH at DESY *. The pickup signal is transported via radiation resistant coaxial cables to the electro-optic modulator (EOM) **. Due to the high losses of the 40 GHz RF front-end the signal in the RF path is attenuated well below the optimal operation voltage of the EOM. To improve the overall performance, the signal strength of the induced pickup signal needs to be increased and at the same time the losses in the RF front-end significantly reduced. In this paper, the analysis towards improving the induced pickup signal strength is presented. Simulations are performed with the CST STUDIO SUITE package and the results are compared with the state of the art high bandwidth pickups.
* A. Angelovski et al., Phys. Rev. ST Accel. Beams 15, 112803 (2012)
** A. Penirschke et al., Proc. of IBIC2012, Tsukuba, Japan (2012)

THBL1

RF Heating from Wake Losses in Diagnostics Structures

longitudinal, LHC, impedance, simulation

929

E. Métral
CERN, Geneva, Switzerland

Heating of diagnostics structures (striplines, buttons, screen vessels, wire scanners etc) has been observed at many facilities with higher stored currents*. Simulations of wake losses using 3D EM codes are regularly used to estimate the amount of power lost from the bunched beam but on its own this does not tell how much is radiated back into the beam pipe or transmitted into external ports and how much is actually being dissipated in the structure and where. This talk should introduce into the matter, summarise some of the observations at various facilities and illustrate what approaches of detailed simulations have been taken.
* summarizing a workshop at DLS (see http://tinyurl.com/wakeloss )

Slides THBL1 [9.078 MB]