- Durham, North Carolina, United States
jay golden
Duke University, School of the Environment, Department Member
Gas laser action using a charge and current neutralized proton beam as a pump source has been demonstrated. Stimulated emission at 357.7 and 380.5 nm, corresponding to the v' = o transfers to v'' = 1 and v' = o... more
Gas laser action using a charge and current neutralized proton beam as a pump source has been demonstrated. Stimulated emission at 357.7 and 380.5 nm, corresponding to the v' = o transfers to v'' = 1 and v' = o transfers to v'' = 2 transitions of the Nâ(C transfers to B) band, has been observed in Ar/5%Nâ gas mixtures. In comparison with electron beams, protons appear to be more efficient for excitation sources of high pressure UV and visible lasers.
Research Interests:
Results are reported on the generation of MeV, pulsed ion beams at a peak power level in excess of 2 X 10 to the 11th power watts that have an angular divergence of about 3 deg - 4 deg. Such beams can be used in the formation of field... more
Results are reported on the generation of MeV, pulsed ion beams at a peak power level in excess of 2 X 10 to the 11th power watts that have an angular divergence of about 3 deg - 4 deg. Such beams can be used in the formation of field reversing proton rings.
Research Interests:
The diffusion of an external magnetic field through a toroidal conducting shell is studied under the assumption of a small aspect ratio. The external magnetic field can have an arbitrary field index and magnetic flux on the minor axis of... more
The diffusion of an external magnetic field through a toroidal conducting shell is studied under the assumption of a small aspect ratio. The external magnetic field can have an arbitrary field index and magnetic flux on the minor axis of the torus. The diffused field, field index, magnetic flux and wall current are computed analytically and compared with the numerical results from the TRIDIF code. The analytical and numerical results are in good agreement. Measurements in the toroidal chamber of the modified betatron gave a delay time of 34 microseconds, which is less than 10% from the theoretical prediction fo 37 microseconds.
Research Interests:
We have developed two strong focusing field configurations that provide high midplane accessibility and therefore are compatible with presently contemplated extraction schemes for high-current, toroidal accelerators. When these windings... more
We have developed two strong focusing field configurations that provide high midplane accessibility and therefore are compatible with presently contemplated extraction schemes for high-current, toroidal accelerators. When these windings are attached to a modified betatron accelerator, the bandwidth of the device is slightly smaller than the bandwidth of a modified betatron with unsplit stellarator windings. However, the bandwidth of the two new configurations is more than sufficient even for modest (20--30 kA) winding currents.
Research Interests:
ABSTRACT
Experimental results are reported which show that the backward directed (and unusable) ion current in a reflex triode can be almost completely suppressed by adding a second anode, made of aluminized mylar, 0.5 cm from the existing... more
Experimental results are reported which show that the backward directed (and unusable) ion current in a reflex triode can be almost completely suppressed by adding a second anode, made of aluminized mylar, 0.5 cm from the existing polyethylene anode. Proton generation efficiencies in excess of 50% have been obtained.
Research Interests:
The current of an intense, pulsed proton beam is experimentally determined by monitoring prompt gamma rays from nuclear reactions induced in a suitable target. Relevant data are given on the reactions employed including (7)Li(p,gamma)... more
The current of an intense, pulsed proton beam is experimentally determined by monitoring prompt gamma rays from nuclear reactions induced in a suitable target. Relevant data are given on the reactions employed including (7)Li(p,gamma) (8)Be, (19)F(p,alphagamma) (16)O, and (12)C(p,gamma) (13)N so that absolute currents can be determined. This method avoids the complication of target blowoff and the need for attenuating screens when applied to high current density beams.
Research Interests:
Research Interests:
A new reflexing electron ion source is described. The device produces a unidirectional ion beam with relatively high efficiency even when the applied magnetic field exceeds the self field. This new source operates at a low, constant... more
A new reflexing electron ion source is described. The device produces a unidirectional ion beam with relatively high efficiency even when the applied magnetic field exceeds the self field. This new source operates at a low, constant impedance during much of the applied voltage pulse and is better matched to available high-power, low impedance generators than previous reflexing electron devices.
Research Interests:
Research Interests:
This report describes a series of experiments that led to the transient field reversal of the applied magnetic field with a proton pulse. The 400-500 KA, 50 nsec duration, 1.7 MeV peak energy hollow proton pulse is generated by an Inverse... more
This report describes a series of experiments that led to the transient field reversal of the applied magnetic field with a proton pulse. The 400-500 KA, 50 nsec duration, 1.7 MeV peak energy hollow proton pulse is generated by an Inverse Reflex Tetrode. After passing through the cusp, the pulse propagates in a uniform field with 1.15 cm/nsec axial velocity, when the applied voltage on the anode is 1MV.
Research Interests:
Page 1. Jeffry Golden Christos A. Kapetanakos John A. Pasour Redge A. Mahaffey The Generation and Application of ... He is currently a section head in the Beam Dynamics Program at NRL. Christos A. Kapetanakos holds a Ph.D. from the... more
Page 1. Jeffry Golden Christos A. Kapetanakos John A. Pasour Redge A. Mahaffey The Generation and Application of ... He is currently a section head in the Beam Dynamics Program at NRL. Christos A. Kapetanakos holds a Ph.D. from the University of Maryland. ...
Research Interests:
A high-power gas laser pumped by an intense, pulsed, space charge-and current-neutralized ion beam is described. A high-pressure gas in the laser cavity is ionized by an ion beam. Atomic processes occur which result in a population... more
A high-power gas laser pumped by an intense, pulsed, space charge-and current-neutralized ion beam is described. A high-pressure gas in the laser cavity is ionized by an ion beam. Atomic processes occur which result in a population inversion for the excited states of the gas. Coherent radiation is then emitted by the excited gas atoms in the inverted state. The
Research Interests:
Proton beam pumping of Ar-N2 and XeF lasers has been demonstrated. An intense proton beam, generated by a reflex tetrode, is injected into a high pressure gas cell through a 3 microns thick Mylar window. Stimulated emission is obtained... more
Proton beam pumping of Ar-N2 and XeF lasers has been demonstrated. An intense proton beam, generated by a reflex tetrode, is injected into a high pressure gas cell through a 3 microns thick Mylar window. Stimulated emission is obtained from 95% Ar/5% N2 gas mixtures and from Xe/NF3 mixtures diluted by either argon, neon or helium. The XeF laser efficiencies
Research Interests:
ABSTRACT
Research Interests:
Numerical calculations of synchrotron radiation emitted from the modified betatron accelerator show that, for relativistic electron energies up to approximately 2 MeV, the single-particle intensity spectrum is characaterized by a peak at... more
Numerical calculations of synchrotron radiation emitted from the modified betatron accelerator show that, for relativistic electron energies up to approximately 2 MeV, the single-particle intensity spectrum is characaterized by a peak at the Doppler-shifted cyclotron frequency associated with the applied toroidal field. As the electron energy is increased above a few MeV, the calculated spectrum becomes comparable to that of an electron in purely circular motion. Measurements of the radiation using fixed-frequency heterodyne receivers indicate that the polarization, amplitude, and the temporal evolution of radiated power during the first few hundred microseconds of acceleration are in good agreement with the predicted single-particle spectrum. These observations have been used to confirm the energy evolution and provide information about the magnitude of the transverse velocity of the beam electrons. Late-time signal decay suggests that electrons are moving off the minor axis in a manner that is consistent with the excitation of the electron-cyclotron resonance.
Research Interests:
1407_47Since the previously reported successful demonstration of acceleration of electrons to $OM 12 MeV, higher trapped beam current and longer beam lifetime have been obtained. The improved confinement has led to a higher peak energy... more
1407_47Since the previously reported successful demonstration of acceleration of electrons to $OM 12 MeV, higher trapped beam current and longer beam lifetime have been obtained. The improved confinement has led to a higher peak energy $OM 18 MeV, and is the result of increasing the strong focusing and toroidal magnetic fields, reducing magnetic field errors, and optimizing the betatron flux
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There are several approaches to generate high voltage multi-kiloampere electron beams under investigation at the Naval Research Laboratory. Such accelerators could provide compact drivers for high power Free Electron Lasers. Three of... more
There are several approaches to generate high voltage multi-kiloampere electron beams under investigation at the Naval Research Laboratory. Such accelerators could provide compact drivers for high power Free Electron Lasers. Three of these potential FEL drivers are discussed in this paper. They are (1) the Long Pulse Induction Linac, (2) the Racetrack Induction Accelerator and (3) the Modified Betatron.
Research Interests:
... It is apparent from this trace that the proton pulse is triangular with a baseline of about ... Roswell Lee (private communication, to be published); also see R. Lee, CA Kapetanakos, J. Golden, and S ... 3 The differential extension... more
... It is apparent from this trace that the proton pulse is triangular with a baseline of about ... Roswell Lee (private communication, to be published); also see R. Lee, CA Kapetanakos, J. Golden, and S ... 3 The differential extension of the solar limb A is inferred from the light flux past an oc ...
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High-power microwave radiation is observed when a positive pulse is applied to an anode of a reflex triode. The frequency of radiation varies as f approx. V¹²/D/sup n/, where V is the anode voltage, D is the cathode--virtual-cathode... more
High-power microwave radiation is observed when a positive pulse is applied to an anode of a reflex triode. The frequency of radiation varies as f approx. V¹²/D/sup n/, where V is the anode voltage, D is the cathode--virtual-cathode spacing, and 0 < n < or = 1. The basic features of the radiation are explained by a theoretical model which
Research Interests:
ABSTRACT
Research Interests:
Experimental results are reported which show that the backward directed (and unusable) ion current in a reflex triode can be almost completely suppressed by adding a second anode, made of aluminized mylar, 0.5 cm from the existing... more
Experimental results are reported which show that the backward directed (and unusable) ion current in a reflex triode can be almost completely suppressed by adding a second anode, made of aluminized mylar, 0.5 cm from the existing polyethylene anode. Proton generation efficiencies in excess of 50% have been obtained.
Research Interests:
Abstract: Heat islands in urban and suburban areas are created when impervious concrete and asphalt pavements heat up during the day and the heat is released into the atmosphere at night. Peak summertime surface course temperatures can be... more
Abstract: Heat islands in urban and suburban areas are created when impervious concrete and asphalt pavements heat up during the day and the heat is released into the atmosphere at night. Peak summertime surface course temperatures can be as much as 120 degrees ...
ABSTRACT Human forearm oxygenation and scattering changes during ischemia were investigated using picosecond near infrared laser spectroscopy. Path lengths were calculated for different geometries. At 760 nm, a plateau phaser was reached... more
ABSTRACT Human forearm oxygenation and scattering changes during ischemia were investigated using picosecond near infrared laser spectroscopy. Path lengths were calculated for different geometries. At 760 nm, a plateau phaser was reached after 4 min occlusion. No changes were observed during the occlusion at 800 nm, the hemoglobin isosbetic wavelength. Time-resolved Monte Carlo simulations were performed also to mimic the propagation of a light pulse in a forearm phantom containing different quantity and size of polystyrene spheres as scattering media. The influence of both the scattering and absorption effects was studied.© (1991) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
ABSTRACT
Research Interests:
The current of an intense, pulsed proton beam is experimentally determined by monitoring prompt gamma rays from nuclear reactions induced in a suitable target. Relevant data are given on the reactions employed including (7)Li(p,gamma)... more
The current of an intense, pulsed proton beam is experimentally determined by monitoring prompt gamma rays from nuclear reactions induced in a suitable target. Relevant data are given on the reactions employed including (7)Li(p,gamma) (8)Be, (19)F(p,alphagamma) (16)O, and (12)C(p,gamma) (13)N so that absolute currents can be determined. This method avoids the complication of target blowoff and the need for attenuating screens when applied to high current density beams.
Research Interests:
ABSTRACT
Research Interests:
A polarity-reversed 1012-W relativistic-electron-beam generator operating in the self-pinched mode is used to produce and propagate intense proton beams. Charge-neutralized beams of 30-50 ns duration consisting of over 4 × 1016... more
A polarity-reversed 1012-W relativistic-electron-beam generator operating in the self-pinched mode is used to produce and propagate intense proton beams. Charge-neutralized beams of 30-50 ns duration consisting of over 4 × 1016 0.5-0.8-MeV protons distributed over a 120-cm2 cross-sectional area are routinely produced. The 150-200-kA average ion currents deduced from these measurements are in good agreement with theoretical calculations.
Research Interests:
This paper reports on the transient field reversal of the applied magnetic field with a proton pulse. The 400--500-kA (peak), 50-nsec-duration, 1.7-MeV peak-energy hollow proton pulse containing about 8 x 10¹ⶠprotons is generated by... more
This paper reports on the transient field reversal of the applied magnetic field with a proton pulse. The 400--500-kA (peak), 50-nsec-duration, 1.7-MeV peak-energy hollow proton pulse containing about 8 x 10¹ⶠprotons is generated by an inverse reflex tetrode. After passing through a magnetic cusp, the pulse propagates in a 1.5-kG uniform field Bâ with a self-generated magnetic field ..delta..B/sub
Research Interests:
The lifetime of the circulating electron beam in the Naval Research Laboratory modified betatron has been increased by more than 2 orders of magnitude with the addition of strong focusing windings to the device. The injected beam... more
The lifetime of the circulating electron beam in the Naval Research Laboratory modified betatron has been increased by more than 2 orders of magnitude with the addition of strong focusing windings to the device. The injected beam consistently spirals from the injector to the minor axis and is trapped. The ~0.5-kA trapped electron ring has been accelerated above 10 MeV
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ABSTRACT
Research Interests:
The flashover strength of Plexiglas insulators subjected to submicrosecond voltage impulses in vacuum and in the presence of a magnetic field that is perpendicular to the insulator surface is studied. Flashover breakdown strength is... more
The flashover strength of Plexiglas insulators subjected to submicrosecond voltage impulses in vacuum and in the presence of a magnetic field that is perpendicular to the insulator surface is studied. Flashover breakdown strength is reduced by magnetic fields of a few kilogauss. Observation by fast-framing photography does not reveal curvature of the breakdown arc greater than 20°.
Research Interests:
ABSTRACT
Research Interests:
... 9C. W. Roberson, A. Mondelii, and D. Chemin, Phys. Rev. Lett. SO, 507 (1983). roC. A. Kapetanakos, D. Dialetis, and S. i. Marsh, Part, Accel 1987; NRL Memo Report No. 5619 (1985). "CA Kapetanakos, D. Dialetis, and SJ Marsh,... more
... 9C. W. Roberson, A. Mondelii, and D. Chemin, Phys. Rev. Lett. SO, 507 (1983). roC. A. Kapetanakos, D. Dialetis, and S. i. Marsh, Part, Accel 1987; NRL Memo Report No. 5619 (1985). "CA Kapetanakos, D. Dialetis, and SJ Marsh, Nucl. Inst. Methods Phys. Res. 24, 805 (1987). ...