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Papers by Antonio Anselmo

AIP Conference Proceedings, 1987

ABSTRACT In this paper we discuss the potential role of pulse power technology for future high gr... more ABSTRACT In this paper we discuss the potential role of pulse power technology for future high gradient accelerators. Compared to present day pulse power sources the requirements are quite modest and, with the exception of a detailed testing of high repetition rate systems, all components have been tested over several years. We review pulse power technology and its use in collective acceleration of ions and electrons. An account is presented of a new concept for collective electron acceleration through the parametric excitation of fast waves on beams. A summary is given also of achievements in the generation of high power microwave signals, and a discussion presented of structure requirements to take full advantage of the newly evolving ultra high power sources.

Physics of Fluids, 1985

ABSTRACT In this paper, an account is presented of an investigation into the propagation of large... more ABSTRACT In this paper, an account is presented of an investigation into the propagation of large amplitude space-charge waves in an inhomogeneous waveguide. The study is motivated by the possibility of using these waves for the collective acceleration of ions. Measurements are reported that show an increase in the wave phase velocity as the guide diameter, and hence the effective plasma frequency is decreased. Results are also presented which show that the wave phase velocity is a function of its amplitude, and that large amplitude, nonlinear waves propagate more slowly than those described by linear theory. The results demonstrate that it is possible to control the wave propagation characteristics, and therefore indicate the electron-beam-supported slow space-charge waves provide a suitable medium for collective ion acceleration. Finally, a summary is given of possible advantages of an electron beam-wave accelerator over those using externally generated rf fields.

An account will be presented describing the present status of electron beam supported wave accele... more An account will be presented describing the present status of electron beam supported wave accelerator research. We shall review the various approaches to collective acceleration using waves on an electron beam, and then focus attention on ion acceleration in space charge waves. We shall describe the results of experiments on nonlinear wave propagation in inhomogeneous guides. Results will also be presented reviewing work on the use of beat waves on electron beams for collective acceleration. In both cases we shall summarize the status of theoretical studies of these acceleration techniques and will indicate direction for future research.

Summarv The use of parametric scattering as a means of space charge wave growth for a converging ... more Summarv The use of parametric scattering as a means of space charge wave growth for a converging guide, ion accelerator sys-tem is discussed. A 400-600 keV, 1.5-3.0 kA electron beam is passed through a self biasing, electrostatic wiggler in order to grow both slow and fast space charge waves. We present mea-surements of the wave frequency and associated wave fields as a function of the equilibrium. Furthermore, a calculation of the wave kinetic power flow and wave electromagnetic power flow is used to estimate the achievable axial electric field.

Collective wave accelerator schemes utilizing slow waves on an electron beam have an upper energy... more Collective wave accelerator schemes utilizing slow waves on an electron beam have an upper energy limit on the load particles set by the drive beam drift velocity. Typical intense electron beams operating near limiting current have drift velocities between 0.7~ and O.Qc, setting an energy limit for protons of about 1 GeV. In order to collectively accelerate electrons or ions above this limit, the drive wave must have a phase velocity greater than electron beam drift velocity. The Ultralac concept utilizes the fast upper hybrid wave for particle acceleration. It has a phase velocity that is bounded only in the lower limit by the electron drift velocity. Calculations are presented showing the operating parameters of such a device including beam and wave parameters and achievable field gradients, load particle current limits and particle focusing.

IEEE Transactions on Nuclear Science, 1985

Physics of Fluids

ABSTRACT An investigation is reported on the use of parametric scattering from an electrostatic w... more ABSTRACT An investigation is reported on the use of parametric scattering from an electrostatic wiggler for the growth of space charge waves. This investigation extends previous work on slow space charge wave generation and propagation in inhomogeneous waveguides. Observations show that the scattering technique may be used for the growth of large amplitude waves and that this technique permits wave growth at all values of interest for the ratio of beam to limiting current.

In this paper we discuss the potential role of pulse power technology for future high gradient ac... more In this paper we discuss the potential role of pulse power technology for future high gradient accelerators Compared to present day pulse power sources the requirements are quite modest and, with the exception of a detailed testing of high repetition rate systems, all components have been tested over several years. We review pulse power technology and its use in collective acceleration of ions and electron~ An account is presented of a new concept for collective electron acceleration through the parametric excitation of fast waves on besm~ A summary is given also of achievements in the generation of high power microwave signals, and a discussion presented of structure requirements to take full advantage of the newly evolving ultra high power sourcea N, This condition is typically less restrictive than that due to the energy availability for ion

wave accelerator schemes utilizing slow waves on an electron beam have an upper energy limit on t... more wave accelerator schemes utilizing slow waves on an electron beam have an upper energy limit on the load particles set by the drive beam drift velocity. Typical intense electron beams operating near limiting current have drift velocities between 0.7~ and O.Qc, setting an energy limit for protons of about 1 GeV. In order to collectively accelerate electrons or ions above this limit, the drive wave must have a phase velocity greater than electron beam drift velocity.

An investigation of electron beam space charge wave propagation in inhomogeneous waveguides is pr... more An investigation of electron beam space charge wave propagation in inhomogeneous waveguides is presented. Measurement of beam current through slow wave structures, diverging, and converging guides is made with Rogowski coils. Slow space charge waves are grown via coupled cavity structures. Waves are grown to linear and nonlinear amplitudes. Wave azimuthal magnetic field is measured using coupling loops. Wave radial electric field is measured using capacitative probes. Amplitude is measured using crystal detectors and mixers. Wave coherence is measured with the transform of the mixed signal. The phase shift between a pair of fixed probes determines wavenumber. Quadrature phase detectors time resolve mode amplitude and wavelength. Wavelength and frequency determine the phase velocity. Simultaneous measure of phase velocity in various guide diameters demonstrate boundary condition wave velocity control. Wave axial electric field is measured using the wavenumber and perpendicular field magnitude. Growth of slow and fast space charge waves parametrically via self-biased electrostatic wigglers is investigated. The wiggler periodic potential is created by capacitively dividing the potential drop associated with the electron beam. Capacitive probes and Rogowski coils measure beam to wall potential, current, and average electron drift velocity. Beams propagated through the structure show little energy loss. Large amplitude modes are excited on the beam with a finite frequency mismatch. Mixers measure the separate eigenmode frequencies. The relative amplitudes of the eigenmodes was measured using crystal detectors. Axial magnetic fields associated with the sapce charge waves indicate that they are mixed modes. An optimized converging guide accelerator is studied using the linear theory. Accelerator start velocity is minimized while wave self-trapping field is maximized. Input and output parameters for a low and moderate beta proton accelerator are presented. Possible use of cyclotron waves in a resonant collective accelerator for ultra-relativistic particles is studied. The cyclotron wave is the only beam eigenmode that has a phase velocity equal to the speed of light and a component electric field along axis. Calculation of the quasi-static dispersion relationship determines the device operating frequency. Calculation of the relative axial fields associated with the modes is presented.

AIP Conference Proceedings, 1987

ABSTRACT In this paper we discuss the potential role of pulse power technology for future high gr... more ABSTRACT In this paper we discuss the potential role of pulse power technology for future high gradient accelerators. Compared to present day pulse power sources the requirements are quite modest and, with the exception of a detailed testing of high repetition rate systems, all components have been tested over several years. We review pulse power technology and its use in collective acceleration of ions and electrons. An account is presented of a new concept for collective electron acceleration through the parametric excitation of fast waves on beams. A summary is given also of achievements in the generation of high power microwave signals, and a discussion presented of structure requirements to take full advantage of the newly evolving ultra high power sources.

Physics of Fluids, 1985

ABSTRACT In this paper, an account is presented of an investigation into the propagation of large... more ABSTRACT In this paper, an account is presented of an investigation into the propagation of large amplitude space-charge waves in an inhomogeneous waveguide. The study is motivated by the possibility of using these waves for the collective acceleration of ions. Measurements are reported that show an increase in the wave phase velocity as the guide diameter, and hence the effective plasma frequency is decreased. Results are also presented which show that the wave phase velocity is a function of its amplitude, and that large amplitude, nonlinear waves propagate more slowly than those described by linear theory. The results demonstrate that it is possible to control the wave propagation characteristics, and therefore indicate the electron-beam-supported slow space-charge waves provide a suitable medium for collective ion acceleration. Finally, a summary is given of possible advantages of an electron beam-wave accelerator over those using externally generated rf fields.

An account will be presented describing the present status of electron beam supported wave accele... more An account will be presented describing the present status of electron beam supported wave accelerator research. We shall review the various approaches to collective acceleration using waves on an electron beam, and then focus attention on ion acceleration in space charge waves. We shall describe the results of experiments on nonlinear wave propagation in inhomogeneous guides. Results will also be presented reviewing work on the use of beat waves on electron beams for collective acceleration. In both cases we shall summarize the status of theoretical studies of these acceleration techniques and will indicate direction for future research.

Summarv The use of parametric scattering as a means of space charge wave growth for a converging ... more Summarv The use of parametric scattering as a means of space charge wave growth for a converging guide, ion accelerator sys-tem is discussed. A 400-600 keV, 1.5-3.0 kA electron beam is passed through a self biasing, electrostatic wiggler in order to grow both slow and fast space charge waves. We present mea-surements of the wave frequency and associated wave fields as a function of the equilibrium. Furthermore, a calculation of the wave kinetic power flow and wave electromagnetic power flow is used to estimate the achievable axial electric field.

Collective wave accelerator schemes utilizing slow waves on an electron beam have an upper energy... more Collective wave accelerator schemes utilizing slow waves on an electron beam have an upper energy limit on the load particles set by the drive beam drift velocity. Typical intense electron beams operating near limiting current have drift velocities between 0.7~ and O.Qc, setting an energy limit for protons of about 1 GeV. In order to collectively accelerate electrons or ions above this limit, the drive wave must have a phase velocity greater than electron beam drift velocity. The Ultralac concept utilizes the fast upper hybrid wave for particle acceleration. It has a phase velocity that is bounded only in the lower limit by the electron drift velocity. Calculations are presented showing the operating parameters of such a device including beam and wave parameters and achievable field gradients, load particle current limits and particle focusing.

IEEE Transactions on Nuclear Science, 1985

Physics of Fluids

ABSTRACT An investigation is reported on the use of parametric scattering from an electrostatic w... more ABSTRACT An investigation is reported on the use of parametric scattering from an electrostatic wiggler for the growth of space charge waves. This investigation extends previous work on slow space charge wave generation and propagation in inhomogeneous waveguides. Observations show that the scattering technique may be used for the growth of large amplitude waves and that this technique permits wave growth at all values of interest for the ratio of beam to limiting current.

In this paper we discuss the potential role of pulse power technology for future high gradient ac... more In this paper we discuss the potential role of pulse power technology for future high gradient accelerators Compared to present day pulse power sources the requirements are quite modest and, with the exception of a detailed testing of high repetition rate systems, all components have been tested over several years. We review pulse power technology and its use in collective acceleration of ions and electron~ An account is presented of a new concept for collective electron acceleration through the parametric excitation of fast waves on besm~ A summary is given also of achievements in the generation of high power microwave signals, and a discussion presented of structure requirements to take full advantage of the newly evolving ultra high power sourcea N, This condition is typically less restrictive than that due to the energy availability for ion

wave accelerator schemes utilizing slow waves on an electron beam have an upper energy limit on t... more wave accelerator schemes utilizing slow waves on an electron beam have an upper energy limit on the load particles set by the drive beam drift velocity. Typical intense electron beams operating near limiting current have drift velocities between 0.7~ and O.Qc, setting an energy limit for protons of about 1 GeV. In order to collectively accelerate electrons or ions above this limit, the drive wave must have a phase velocity greater than electron beam drift velocity.

An investigation of electron beam space charge wave propagation in inhomogeneous waveguides is pr... more An investigation of electron beam space charge wave propagation in inhomogeneous waveguides is presented. Measurement of beam current through slow wave structures, diverging, and converging guides is made with Rogowski coils. Slow space charge waves are grown via coupled cavity structures. Waves are grown to linear and nonlinear amplitudes. Wave azimuthal magnetic field is measured using coupling loops. Wave radial electric field is measured using capacitative probes. Amplitude is measured using crystal detectors and mixers. Wave coherence is measured with the transform of the mixed signal. The phase shift between a pair of fixed probes determines wavenumber. Quadrature phase detectors time resolve mode amplitude and wavelength. Wavelength and frequency determine the phase velocity. Simultaneous measure of phase velocity in various guide diameters demonstrate boundary condition wave velocity control. Wave axial electric field is measured using the wavenumber and perpendicular field magnitude. Growth of slow and fast space charge waves parametrically via self-biased electrostatic wigglers is investigated. The wiggler periodic potential is created by capacitively dividing the potential drop associated with the electron beam. Capacitive probes and Rogowski coils measure beam to wall potential, current, and average electron drift velocity. Beams propagated through the structure show little energy loss. Large amplitude modes are excited on the beam with a finite frequency mismatch. Mixers measure the separate eigenmode frequencies. The relative amplitudes of the eigenmodes was measured using crystal detectors. Axial magnetic fields associated with the sapce charge waves indicate that they are mixed modes. An optimized converging guide accelerator is studied using the linear theory. Accelerator start velocity is minimized while wave self-trapping field is maximized. Input and output parameters for a low and moderate beta proton accelerator are presented. Possible use of cyclotron waves in a resonant collective accelerator for ultra-relativistic particles is studied. The cyclotron wave is the only beam eigenmode that has a phase velocity equal to the speed of light and a component electric field along axis. Calculation of the quasi-static dispersion relationship determines the device operating frequency. Calculation of the relative axial fields associated with the modes is presented.