NAPAC2016 - List of Keywords (ECR)

Paper	Title	Other Keywords	Page
MOPOB05	Tokamak Accelerator	ion, plasma, vacuum, experiment	76
	G. Li ASIPP, Hefei, People's Republic of China
	Tokamak accelerator within plasma is analyzed to be implemented in existing machines for speeding the development of fusion energy with seeding fast particles from high current accelerators - the so-called two-component reactor approach [J. M. Dawson, H. P. Furth, and F. H. Tenney, Phys. Rev. Lett. 26, 1156 (1971)]. All plasma particles are heated at the same time by inductively-coupled power transfer (IPT) within an energy confinement time. This could facilitate the attainment of ignition in tokamak by forming high-gain high-field (HGHF) fusion plasma suggested in [Li. G., Sci. Rep.5, 15790 (2015)]. HGHF mechanism is validated by the flux-conserving process existed in discharges of tokamak plasma at normal operation with long pulses or at compression process within an energy confinement time. Differences between HGHF plasma and former unity-beta plasma are discussed. Tokamak as an accelerator could scale down the design capacity of fusion power plant by simply inserting in-vacuum vertical field coils (IVC) within its vacuum vessel, such as China Fusion Engineering Test Reactor (CFETR).
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-MOPOB05
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MOPOB20	Enhancement of the Accelerating Gradient in Superconducting Microwave Resonators	ion, cavity, induction, accelerating-gradient	113
	M. Checchin, A. Grassellino, M. Martinello, S. Posen, A. Romanenko Fermilab, Batavia, Illinois, USA M. Martinello Illinois Institute of Technology, Chicago, Illlinois, USA J. Zasadzinski IIT, Chicago, Illinois, USA
	The accelerating gradient of superconducting resonators can be enhanced by engineering the thickness of a dirty layer grown at the cavity's rf surface. In this paper the description of the physics behind the accelerating gradient enhancement by meaning of the dirty layer is carried out by solving numerically the the Ginzburg-Landau (GL) equations for the layered system. The calculation shows that the presence of the dirty layer stabilizes the Meissner state up to the lower critical field of the bulk, increasing the maximum accelerating gradient.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-MOPOB20
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MOPOB39	A 600 Volt Multi-Stage, High Repetition Rate GaN FET Switch	ion, linac, electron, operation	152
	G.W. Saewert, D. Frolov, H. Pfeffer Fermilab, Batavia, Illinois, USA
	Using recently available GaN FETs, a 600 Volt three-stage, multi-FET switch has been developed having 2 nanosecond rise time driving a 200 Ω load with the potential of approaching 30 MHz average switching rates. Possible applications include driving particle beam choppers kicking bunch-by-bunch and beam deflectors where the rise time needs to be custom tailored. This paper reports on the engineering issues addressed, the design approach taken and some performance results of this switch.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-MOPOB39
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MOPOB65	Investigation of the Origin of the Anti-Q-Slope	ion, cavity, experiment, SRF	218
	J.T. Maniscalco, M. Ge, D. Gonnella, M. Liepe Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
	The surface resistance of a superconductor, a property very relevant to SRF accelerators, has long been known to depend on the strength of the surface magnetic field. A recent discovery showed that, for certain surface treatments, microwave cavities can be shown to have an inverse field dependence, dubbed the ‘‘anti-Q-slope'', in which the surface resistance decreases over an increasing field. Here we present an investigation into what causes the anti-Q-slope in nitrogen-doped niobium cavities, drawing a direct connection between the electron mean free path of the SRF material and the magnitude of the anti-Q-slope. Further, we incorporate residual resistance due to flux trapping to calculate an optimal mean free path for a given trapped flux.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-MOPOB65
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TUPOA54	Examination of Out-of-Field Dose and Penumbral Width of Flattening Filter Free Beams in Medical Linear Accelerators	ion, photon, linac, radiation	396
	L.C. Bennett, O.N. Vassiliev M.D.A.C.C., Houston, Texas, USA
	Medical linear accelerators (LINACS) have traditionally used a flattening filter to ensure that the photon spectrum entering the patient was homogeneous within a given field size. Recently, leading manufacturers of medical accelerators have begun including an option for Flattening Filter Free (FFF) beams on their accelerators. These beams are characterized by a softer spectrum (lower average energy), peaked profiles, and less side scatter. Previous work with Monte Carlo models has shown that the elimination of the flattening filter from the beam path has the potential to greatly reduce scatter in regions immediately adjacent to the primary field (Kry 2010); however, systematic in-depth investigation of these effects has yet to be done using actual measurements from a linac equipped with FFF beams. We have examined and compared measurements of different energy pairings of FFF and FF beams from the Varian TrueBeam accelerators and found reductions of peripheral dose at upwards of 30% for the FFF beams and nearly 5% reduction in penumbral width at nearly all depths and field sizes; reductions were greatest for shallow depths and small field size. Kry et al. Out-of-field photon dose following removal of the flattening filter from a medical accelerator. Physics in Medicine and Biology. vol. 55, no. 8, 2010. pp 2155-2166.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-TUPOA54
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TUPOB50	Beam-Induced Heating of the Kicker Ceramics Chambers at NSLS-II	ion, kicker, impedance, injection	599
	A. Blednykh, B. Bacha, G. Bassi, G. Ganetis, C. Hetzel, H.-C. Hseuh, T.V. Shaftan, V.V. Smaluk, G.M. Wang BNL, Upton, Long Island, New York, USA
	Funding: This work was supported by Department of Energy contract DE-AC02-98CH10886. First experience with the beam-induced heating of the ceramics chambers in the NSLS-II storage ring has been discussed. Total five ceramics chambers are considered to be replaced due to overheating concern during of upcoming I_av=500mA operations. The air cooling fans has been installed as a temporarily solution to remove heat.
	Poster TUPOB50 [1.629 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-TUPOB50
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WEA4CO03	Intrinsic Landau Damping of Space Charge Modes at Coupling Resonance	ion, resonance, damping, coupling	863
	A. Macridin, J.F. Amundson, A.V. Burov, P. Spentzouris, E.G. Stern Fermilab, Batavia, Illinois, USA
	Funding: This work was performed at Fermilab, operated by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the United States Department of Energy. Using Synergia accelerator modeling package and Dynamic Mode Decomposition technique, the properties of the first transverse dipole mode in Gaussian bunches with space charge are compared at transverse coupling resonance and off-resonance. The Landau damping at coupling resonance and in the strong space charge regime is a factor of two larger, while the mode's tune and shape are nearly the same. While the damping mechanism in the off-resonance case fits well with the classical Landau damping paradigm, the enhancement at coupling resonance is due to a higher order mode-particle coupling term which is modulated by the amplitude oscillation of the resonance trapped particles.
	Slides WEA4CO03 [3.422 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-WEA4CO03
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WEPOB41	Quality Factor in High Power Tests of Cryogenic Copper Accelerating Cavities	ion, cavity, experiment, GUI	987
	A.D. Cahill, J.B. Rosenzweig UCLA, Los Angeles, California, USA V.A. Dolgashev, M.A. Franzi, S.G. Tantawi, S.P. Weathersby SLAC, Menlo Park, California, USA
	Funding: Research made possible by DOE SCGSR and DOE/SU Contract DE-AC02-76-SF00515 Recent SLAC experiments with cryogenically cooled 11.4 GHz standing wave copper accelerating cavities have shown evidence of 250 MV/m accelerating gradients with low breakdown rates. The gradient depends on the circuit parameters of the accelerating cavity, such as the intrinsic and external quality factors (Q0, QE). In our studies we see evidence that Q₀ decreases during rf pulse at 7-70 K. This paper discusses experiments that are directed towards understanding the change of Q0 at high power.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-WEPOB41
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THPOA63	Septum Magnet Design for APS-U	ion, septum, injection, multipole	1231
	M. Abliz, M. Borland, H. Cease, G. Decker, M.S. Jaski, J.S. Kerby, U. Wienands, A. Xiao ANL, Argonne, Illinois, USA
	Funding: * Work supported by the U. S. Department of Energy, Office of Science, under Contract No. DE AC02 06CH11357 The Advanced Photon Source is in the process of developing an upgrade (APS-U) of the storage ring from a double-bend to a multi-bend lattice. A swap-out injection is planned for the APS-U lattice to keep a constant beam current and accommodate small, dynamic aperture. A septum magnet that has a minimum thickness of 2 mm with an injection field of 1.06 T has been designed. The stored beam chamber has an 8 mm x 6 mm super-ellipsoidal aperture. The required total deflecting angle is 89 mrad with a ring energy of 6 GeV. The magnet is straight, but is tilted in yaw, roll, and pitch from the stored beam chamber in order to meet the swap out injection requirements for the APS-U lattice. In order to minimize the leakage field inside the stored beam chamber, four different techniques were utilized in the design. As a result, the horizontal deflecting angle of the stored beam was held to only 5 μrad, and the integrated skew quadrupole inside the stored beam chamber was held to 0.09 T. The detailed techniques that were applied to the design, the field multipoles, and the resulting trajectories of the injected and stored beams are reported.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-THPOA63
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

Paper

Title

Other Keywords

Page

MOPOB05

Tokamak Accelerator

ion, plasma, vacuum, experiment

76

G. Li
ASIPP, Hefei, People's Republic of China

Tokamak accelerator within plasma is analyzed to be implemented in existing machines for speeding the development of fusion energy with seeding fast particles from high current accelerators - the so-called two-component reactor approach [J. M. Dawson, H. P. Furth, and F. H. Tenney, Phys. Rev. Lett. 26, 1156 (1971)]. All plasma particles are heated at the same time by inductively-coupled power transfer (IPT) within an energy confinement time. This could facilitate the attainment of ignition in tokamak by forming high-gain high-field (HGHF) fusion plasma suggested in [Li. G., Sci. Rep.5, 15790 (2015)]. HGHF mechanism is validated by the flux-conserving process existed in discharges of tokamak plasma at normal operation with long pulses or at compression process within an energy confinement time. Differences between HGHF plasma and former unity-beta plasma are discussed. Tokamak as an accelerator could scale down the design capacity of fusion power plant by simply inserting in-vacuum vertical field coils (IVC) within its vacuum vessel, such as China Fusion Engineering Test Reactor (CFETR).

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-MOPOB05

Export •

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MOPOB20

Enhancement of the Accelerating Gradient in Superconducting Microwave Resonators

ion, cavity, induction, accelerating-gradient

113

M. Checchin, A. Grassellino, M. Martinello, S. Posen, A. Romanenko
Fermilab, Batavia, Illinois, USA
M. Martinello
Illinois Institute of Technology, Chicago, Illlinois, USA
J. Zasadzinski
IIT, Chicago, Illinois, USA

The accelerating gradient of superconducting resonators can be enhanced by engineering the thickness of a dirty layer grown at the cavity's rf surface. In this paper the description of the physics behind the accelerating gradient enhancement by meaning of the dirty layer is carried out by solving numerically the the Ginzburg-Landau (GL) equations for the layered system. The calculation shows that the presence of the dirty layer stabilizes the Meissner state up to the lower critical field of the bulk, increasing the maximum accelerating gradient.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-MOPOB20

Export •

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MOPOB39

A 600 Volt Multi-Stage, High Repetition Rate GaN FET Switch

ion, linac, electron, operation

152

G.W. Saewert, D. Frolov, H. Pfeffer
Fermilab, Batavia, Illinois, USA

Using recently available GaN FETs, a 600 Volt three-stage, multi-FET switch has been developed having 2 nanosecond rise time driving a 200 Ω load with the potential of approaching 30 MHz average switching rates. Possible applications include driving particle beam choppers kicking bunch-by-bunch and beam deflectors where the rise time needs to be custom tailored. This paper reports on the engineering issues addressed, the design approach taken and some performance results of this switch.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-MOPOB39

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPOB65

Investigation of the Origin of the Anti-Q-Slope

ion, cavity, experiment, SRF

218

J.T. Maniscalco, M. Ge, D. Gonnella, M. Liepe
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

The surface resistance of a superconductor, a property very relevant to SRF accelerators, has long been known to depend on the strength of the surface magnetic field. A recent discovery showed that, for certain surface treatments, microwave cavities can be shown to have an inverse field dependence, dubbed the ‘‘anti-Q-slope'', in which the surface resistance decreases over an increasing field. Here we present an investigation into what causes the anti-Q-slope in nitrogen-doped niobium cavities, drawing a direct connection between the electron mean free path of the SRF material and the magnitude of the anti-Q-slope. Further, we incorporate residual resistance due to flux trapping to calculate an optimal mean free path for a given trapped flux.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-MOPOB65

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPOA54

Examination of Out-of-Field Dose and Penumbral Width of Flattening Filter Free Beams in Medical Linear Accelerators

ion, photon, linac, radiation

396

L.C. Bennett, O.N. Vassiliev
M.D.A.C.C., Houston, Texas, USA

Medical linear accelerators (LINACS) have traditionally used a flattening filter to ensure that the photon spectrum entering the patient was homogeneous within a given field size. Recently, leading manufacturers of medical accelerators have begun including an option for Flattening Filter Free (FFF) beams on their accelerators. These beams are characterized by a softer spectrum (lower average energy), peaked profiles, and less side scatter. Previous work with Monte Carlo models has shown that the elimination of the flattening filter from the beam path has the potential to greatly reduce scatter in regions immediately adjacent to the primary field (Kry 2010); however, systematic in-depth investigation of these effects has yet to be done using actual measurements from a linac equipped with FFF beams. We have examined and compared measurements of different energy pairings of FFF and FF beams from the Varian TrueBeam accelerators and found reductions of peripheral dose at upwards of 30% for the FFF beams and nearly 5% reduction in penumbral width at nearly all depths and field sizes; reductions were greatest for shallow depths and small field size.
Kry et al. Out-of-field photon dose following removal of the flattening filter from a medical accelerator. Physics in Medicine and Biology. vol. 55, no. 8, 2010. pp 2155-2166.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-TUPOA54

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPOB50

Beam-Induced Heating of the Kicker Ceramics Chambers at NSLS-II

ion, kicker, impedance, injection

599

A. Blednykh, B. Bacha, G. Bassi, G. Ganetis, C. Hetzel, H.-C. Hseuh, T.V. Shaftan, V.V. Smaluk, G.M. Wang
BNL, Upton, Long Island, New York, USA

Funding: This work was supported by Department of Energy contract DE-AC02-98CH10886.
First experience with the beam-induced heating of the ceramics chambers in the NSLS-II storage ring has been discussed. Total five ceramics chambers are considered to be replaced due to overheating concern during of upcoming I_av=500mA operations. The air cooling fans has been installed as a temporarily solution to remove heat.

Poster TUPOB50 [1.629 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-TUPOB50

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEA4CO03

Intrinsic Landau Damping of Space Charge Modes at Coupling Resonance

ion, resonance, damping, coupling

863

A. Macridin, J.F. Amundson, A.V. Burov, P. Spentzouris, E.G. Stern
Fermilab, Batavia, Illinois, USA

Funding: This work was performed at Fermilab, operated by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the United States Department of Energy.
Using Synergia accelerator modeling package and Dynamic Mode Decomposition technique, the properties of the first transverse dipole mode in Gaussian bunches with space charge are compared at transverse coupling resonance and off-resonance. The Landau damping at coupling resonance and in the strong space charge regime is a factor of two larger, while the mode's tune and shape are nearly the same. While the damping mechanism in the off-resonance case fits well with the classical Landau damping paradigm, the enhancement at coupling resonance is due to a higher order mode-particle coupling term which is modulated by the amplitude oscillation of the resonance trapped particles.

Slides WEA4CO03 [3.422 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-WEA4CO03

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPOB41

Quality Factor in High Power Tests of Cryogenic Copper Accelerating Cavities

ion, cavity, experiment, GUI

987

A.D. Cahill, J.B. Rosenzweig
UCLA, Los Angeles, California, USA
V.A. Dolgashev, M.A. Franzi, S.G. Tantawi, S.P. Weathersby
SLAC, Menlo Park, California, USA

Funding: Research made possible by DOE SCGSR and DOE/SU Contract DE-AC02-76-SF00515
Recent SLAC experiments with cryogenically cooled 11.4 GHz standing wave copper accelerating cavities have shown evidence of 250 MV/m accelerating gradients with low breakdown rates. The gradient depends on the circuit parameters of the accelerating cavity, such as the intrinsic and external quality factors (Q0, QE). In our studies we see evidence that Q₀ decreases during rf pulse at 7-70 K. This paper discusses experiments that are directed towards understanding the change of Q0 at high power.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-WEPOB41

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPOA63

Septum Magnet Design for APS-U

ion, septum, injection, multipole

1231

M. Abliz, M. Borland, H. Cease, G. Decker, M.S. Jaski, J.S. Kerby, U. Wienands, A. Xiao
ANL, Argonne, Illinois, USA

Funding: * Work supported by the U. S. Department of Energy, Office of Science, under Contract No. DE AC02 06CH11357
The Advanced Photon Source is in the process of developing an upgrade (APS-U) of the storage ring from a double-bend to a multi-bend lattice. A swap-out injection is planned for the APS-U lattice to keep a constant beam current and accommodate small, dynamic aperture. A septum magnet that has a minimum thickness of 2 mm with an injection field of 1.06 T has been designed. The stored beam chamber has an 8 mm x 6 mm super-ellipsoidal aperture. The required total deflecting angle is 89 mrad with a ring energy of 6 GeV. The magnet is straight, but is tilted in yaw, roll, and pitch from the stored beam chamber in order to meet the swap out injection requirements for the APS-U lattice. In order to minimize the leakage field inside the stored beam chamber, four different techniques were utilized in the design. As a result, the horizontal deflecting angle of the stored beam was held to only 5 μrad, and the integrated skew quadrupole inside the stored beam chamber was held to 0.09 T. The detailed techniques that were applied to the design, the field multipoles, and the resulting trajectories of the injected and stored beams are reported.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-THPOA63

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)