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P.I.G. sputter source for negative metal ions

Description: From meeting on the American physical society; Washington, District of Columbia, USA (23 Apr 1973). Operating parameters for a cathode sputtering P. I. G. ion source with radial extraction for negative metal ion beam production for injection into the University of Wisconsin tandem accelerator are discussed. Beam emittance and beam intensity measurements are discussed. (WHK)
Date: April 30, 1974
Creator: Smith, H.V. Jr. & Richards, H.T.
Partner: UNT Libraries Government Documents Department

Spectroscopic measurements of an H/sup -/ ion source discharge

Description: Spectral emission lines from an H/sup -/ Penning surface-plasma source (SPS), the 4X source, are examined in the visible and near ultraviolet. Electron distribution temperatures are deduced from integral line-strength measurements. These temperatures are surprisingly low, about 0.5 eV. Electron density values of about 1.5 x 10/sup 14/ cm/sup -3/ and H-atom energies between 2 and 2.6 eV are determined from the measured Balmer-line profiles. Assuming the H/sup -/ energy is identical to the H-atom energy, an emittance limit of 0.006 ..pi.. x cm x mrad is deduced for this source with a 5.4-mm aperture.
Date: January 1, 1985
Creator: Keller, R. & Smith, H.V. Jr.
Partner: UNT Libraries Government Documents Department

H/sup -/ beam emittance measurements for the penning and the asymmetric, grooved magnetron surface-plasma sources

Description: Beam-intensity and emittance measurements show that the H/sup -/ beam from our Penning surface-plasma source (SPS) has twice the intensity and ten times the brightness of the H/sup -/ beam from an asymmetric, grooved magnetron SPS. We deduce H/sup -/ ion temperatures of 5 eV for the Penning SPS and 22 eV for the asymmetric, grooved magnetron.
Date: January 1, 1981
Creator: Smith, H.V. Jr. & Allison, P.W.
Partner: UNT Libraries Government Documents Department

Pulsed H beams from Penning SPS (Surface-Plasma Sources) sources equipped with circular emitters

Description: We report the H beam currents and emittances produced when Penning Surface-Plasma Sources (SPS), equipped with circular emitters, are pulsed at /approximately/1% duty factor. Two sources are now under investigation: the small-angle source (SAS) and the 4X source. The 4X source is designed to test the plasma scaling laws for Penning SPS; SAS is the 1X device. The 0.16 cmT discharge volume of the SAS is /approximately/30 times smaller than that of the 4X source, 4.6 cmT. With a 0.25-cm-diam circular emitter, the SAS produces 82 mA of 27-keV H beam with normalized rms emittance of 0.0053 x 0.0056 ( /center dot/cm/center dot/mrad)S. With a 0.26-cm-diam circular emitter, the 4X source produces 50 mA of 29-keV H beam with emittance of 0.0049 x 0.0050 ( /center dot/cm/center dot/mrad)S. The measured data are compared with the predictions of the ion-optical code SNOW. 10 refs., 7 figs., 1 tab.
Date: January 1, 1988
Creator: Smith, H.V. Jr.; Sherman, J.D. & Allison, P.
Partner: UNT Libraries Government Documents Department

4X source

Description: Our Penning surface-plasma source (SPS) discharge chamber was enlarged 4X in two dimensions. To date, three pulsed discharge modes have been studied: two with noisy arc (greater than or equal to 20% H/sup -/ current fluctuations) and one with quiescent arc (less than or equal to 1% H/sup -/ current fluctuations). Lower arc magnetic field and higher H/sub 2/ gas flow allow switching from the noisy to the quiescent mode. The noisy modes yield up to 120 mA of 29-keV H/sup -/ beam; for 110 mA at 29 keV, the two-dimensional normalized rms emittance is 0.017 x 0.018 ..pi...cm.mrad. The quiescent mode yields 75 mA of 29-keV H/sup -/beam; for 67 mA at 24 keV, the emittance is 0.011 x 0.012 ..pi...cm.mrad.
Date: January 1, 1985
Creator: Smith, H.V. Jr.; Allison, P. & Sherman, J.D.
Partner: UNT Libraries Government Documents Department

Spectroscopic investigation of H/sup -/ and D/sup -/ ion source plasmas

Description: Several H I (Balmer), Cs I, Cs II, and Mo I lines emitted by the small-angle source and 4X source plasmas are studied. After correcting for Stark broadening, the H/sub ..cap alpha../ line width gives the H-atom temperature kT/sub H/o. After correcting for Doppler broadening, the H/sub ..beta../ and H/sub delta/ line widths give the electron density n/sub e/. For pulsed operation of both sources, kT/sub H/o is 1.5 to 2 eV and n/sub e/ is 1 to 2 x 10/sup 14//cm/sup 3/, with kT/sub H/o and n/sub e/ scaling approximately with the square root of the discharge current. For the 4X source operated on D/sub 2/, kT/sub D/o and n/sub e/ are near the values of kT/sub H/o and n/sub e/ obtained for H/sub 2/ operation. Assuming that the H/sup -//D/sup -/ ion temperature equals the H/D-atom temperature, we deduce a lower limit to the H/sup -//D/sup -/ beam emittance.
Date: October 1, 1986
Creator: Smith, H.V. Jr.; Allison, P. & Keller, R.
Partner: UNT Libraries Government Documents Department

Scaled, circular-emitter Penning SPS for intense H/sup -/ beams

Description: The Los Alamos versions of the Penning Surface-Plasma Source (SPS) routinely generate H/sup -/ ion beams with pulsed currents over 100 mA. However, these sources employ geometries that result in the extraction of slit beams (0.5 x 10 mm/sup 2/). Our modeling with the SNOW code indicates that the beam from a 5.4-mm-diam circular emitter will have lower emittance and divergence for transport to and injection into our radio-frequency quadrupole (RFQ) accelerator. This paper describes a newly constructed Penning SPS that has most of its discharge chamber dimensions scaled up by a factor of 4 to accommodate this circular emitter.
Date: January 1, 1983
Creator: Smith, H.V. Jr.; Allison, P. & Sherman, J.D.
Partner: UNT Libraries Government Documents Department

H/sup -/ ion source research at Los Alamos

Description: Up to 160 mA of H/sup -/ ions has been extracted at 20 kV from a 10 by 0.5-mm/sup 2/ slit in a Penning surface-plasma source. Typically, 70% of the beam can be transported through a bending magnet to a Faraday cup or emittance scanner. Up to 90% transmission has been observed for some neutralizing gases. Average and pulsed cesium flows from the source were measured with a surface-ionization gauge. Operating parameters of the source and measurements of the emittance are reported.
Date: January 1, 1980
Creator: Allison, P.; Smith, H.V. Jr. & Sherman, J.D.
Partner: UNT Libraries Government Documents Department

H/sup -/ beam formation from a Penning surface plasma source using circular emission-extractor electrodes

Description: Circular emission-extractor electrodes are used to extract H/sup -/ ions from a Penning surface-plasma source, with the calculated space-charge limited current being observed. Emittance measurements are extended to include emittance as a function of beam fraction. Comparatively noise-free discharge voltages lead to factor of three reduction in emittance. Equal emittances in the transverse phase spaces are observed for the circular geometries.
Date: January 1, 1980
Creator: Sherman, J.D.; Allison, P. & Smith, H.V. Jr.
Partner: UNT Libraries Government Documents Department

Comparison of measured emittance of an H/sup -/ ion beam with a simple theory

Description: Ion beam phase space is frequently modeled with a simple theory having a few parameters; for example, the Kapchinskii-Vladimirskii (K-V) equations. For a real beam the normalized phase-space density par. delta/sup 2/i/par. delta x par. delta in one transverse plane x, averaged over the other plane y, is usually far from that of a K-V distribution. We develop a simple theory based on plasma ion temperature that under some conditions gives a good description of the measured emittance of our H/sup -/ ion beam at about 15 keV.
Date: June 1, 1981
Creator: Allison, P.; Sherman, J.D. & Smith, H.V. Jr.
Partner: UNT Libraries Government Documents Department

Rotating penning surface-plasma source for dc H/sup -/ beams

Description: The possibility of using a Penning surface-plasma source (SPS) with rotating electrodes to produce dc H/sup -/ beams is investigated. In this rotating ion source (RIS), the average power density on the electrodes is reduced by magnetically confining the discharge to a small region near the emission slit while maintaining the geometry and instantaneous power density of the fixed-electrode Penning SPS. H/sup -/ beam currents (2.5 mA at 100% duty factor, 104 mA at 1.5% duty factor) and two-dimensional normalized emittances (0.036 ..pi.. cm.mrad x 0.009 ..pi.. cm.mrad for 40% of a 1.5-mA, dc H/sup -/ beam) similar to those of the fixed-electrode Penning SPS are produced by the uncooled RIS reported in this paper. The scaling to a 100% duty factor, fully cooled RIS is briefly discussed.
Date: January 1, 1980
Creator: Smith, H.V. Jr.; Allison, P. & Sherman, J.D.
Partner: UNT Libraries Government Documents Department

H sup minus temperature dependencies in a Penning surface-plasma source

Description: Simple analysis of the nearly-Maxwellian angular distribution of the ribbon H{sup {minus}} ions beams extracted from a long, narrow slit on the 8X source yields the H{sup {minus}} temperature, kT{sub H{minus}}. The derived kT{sub H{minus}} are 0.1--0.3 eV for a 2-A dc discharge and 0.7-1.3 eV for a 400-A pulsed discharge. Because this diagnostic method relies on simple electronic techniques, it allows rapid study of the dependencies of kT{sub H{minus}} on the source parameters, such as gas flow and discharge current. These variations of kT{sub H{minus}} in the 8X source are qualitatively similar to those observed for the H-atom temperature, kT{sub H}o, in the 4X source, another Penning surface-plasma source. 10 refs., 4 figs.
Date: January 1, 1991
Creator: Smith, H.V. Jr.; Sherman, J.D.; Geisik, C. & Allison, P.
Partner: UNT Libraries Government Documents Department

H sup minus temperature measurements by a slit diagnostic technique

Description: H{sup {minus}} ion beams are extracted at 5-25 kV from a long, narrow slit on a Penning surface-plasma source (the 8X source). The extraction geometry produces negligible transverse electric fields (focusing effects) along the slit length. Therefore, the ion angular spread reflects the distribution of ion energies at the plasma surface. The angular distributions are measured with an electric-sweep emittance scanner whose slits are oriented normal to the long dimension of the emission slit. The nearly-Maxwellian angular distributions measured over the central portions of the ribbon beam give kT{sub H{sup {minus}}} of 0.1 to 0.2 eV for a 2-A dc discharge and 0.8 to 1.0 eV for 350- to 500-A pulsed discharges. This diagnostic technique has sufficient position resolution to allow measurement of the kT{sub H{sup {minus}}} spatial distributions. It also allows study of the kT{sub H{sup {minus}}} dependencies on ion source parameters (e.g., increasing the H{sub 2} gas flow lowers kT{sub H{sup {minus}}}). 7 refs., 7 figs.
Date: January 1, 1991
Creator: Sherman, J.D.; Smith, H.V. Jr.; Geisik, C. & Allison, P.
Partner: UNT Libraries Government Documents Department

Spatial distributions of the emitting species in a penning surface-plasma source

Description: Using optical spectroscopy we study the spatial and temporal distributions of the H{sub {alpha}}, CsI(4555 {angstrom}), CsII(4604 {angstrom}), and MoI(3903 {angstrom}) emissions lines in a Penning surface-plasma source (SPS). A diagnostic slit exposes the entire SPS discharge gap either parallel or perpendicular to the magnetic field. The spatial and temporal distributions of the emitting species are recorded using a 1-m monochromator. The visible light and the H{sub {alpha}} and CsII(4604 {angstrom}) spatial distributions are also recorded with a video camera. The cesium atomic and ionic light, and molybdenum atomic light, is strongly concentrated near the cathodes; the visible light and the H{sub {alpha}} light is almost uniform in both directions. These measurements are presented and discussed. 6 refs., 6 figs.
Date: January 1, 1990
Creator: Smith, H.V. Jr; Allison, P.; Schneider, J.D. & Saadatmand, K.
Partner: UNT Libraries Government Documents Department

H/sup -/ ion source with high duty factor

Description: The small-angle source (SAS) and 4X source are Penning surface-plasma sources (SPS) that produce high-brightness H/sup -/ ion beams for accelerator applications. However, electrode cooling considerations have limited the duty factor for pulsed operation to 1 to 3% and the maximum cw H/sup -/ beam to 2 to 4 mA. The addition of some active cooling to the 4X source has allowed pulsed operation at 6% duty factor for arc parameters sufficient to produce approx. 100 mA of H/sup -/ beam. More vigorous cooling, now being added, should allow production of cw H/sup -/ beams up to 20 to 40 mA. The cooled electrodes were designed using the predictions of TOPAZ2D, a 2-D transient, conductive heat-transfer code. The latest results, along with the possibility of producing even larger cw II/sup -/ beam currents, will be discussed.
Date: March 16, 1987
Creator: Smith, H.V. Jr.; Schnurr, N.M.; Whitaker, D.H. & Kalash, K.E.
Partner: UNT Libraries Government Documents Department

Simulations of the LEDA LEBT H{sup +} beam

Description: The computer codes TRACE and SCHAR model the Low-Energy Demonstration Accelerator (LEDA) Low-Energy Beam Transport (LEBT) for 75-keV, 110-mA, dc H{sup +} beams. Solenoid-lens location studies verify that the proposed LEBT design gives a near-optimum match to the LEDA RFQ. The desired RFQ transmission ({ge} 90%) and output emittance ({le} 0.22 {pi} mm mrad, transverse) are obtained when PARMTEQM transports the file for the SCHAR-generated optimum beam through the RFQ.
Date: August 1, 1997
Creator: Smith, H.V. Jr.; Sherman, J.D.; Stevens, R.R. Jr. & Young, L.M.
Partner: UNT Libraries Government Documents Department

Comparison of beam simulations with measurements for a 1.25-MeV, CW RFQ

Description: The Low-Energy Demonstration Accelerator (LEDA) injector is tested using the Chalk River Injector Test Stand (CRITS) radio-frequency quadrupole (RFQ) as a diagnostic instrument. Fifty-keV, dc proton beams are injected into the 1.25-MeV, CW RFQ and transported to a beamstop. Computer-simulation-code predictions of the expected beam performance are compared with the measured beam currents and beam profiles. Good agreement is obtained between the measurements and the simulations at the 75-mA design RFQ output current.
Date: December 1998
Creator: Smith, H. V., Jr.; Bolme, G. O.; Sherman, J. D.; Stevens, R. R., Jr.; Young, L. M. & Zaugg, T. J.
Partner: UNT Libraries Government Documents Department

Initial operation of the CW 8X H[sup [minus]] ion source discharge

Description: A pulsed 8[Chi] source was built and the H[sup [minus]] beam current, emittance, and power efficiency were measured. These results were promising, so a cooled, dc version designed for operation at arc power levels up to 30 kW was built. Testing of the CW 8[Chi] source discharge is underway. The design dc power loading on the cathode surface is 900 W/cm[sup 2], considerably higher than achieved in any pervious Penning surface-plasma source (SPS). Thus, the electrode surfaces are cooled with pressurized, hot water. We describe the source and present the initial operating experience and arc test results.
Date: January 1, 1993
Creator: Smith, H.V. Jr.; Allison, P.; Geisik, C.; Schmitt, D.R.; Schneider, J.D. & Stelzer, J.E.
Partner: UNT Libraries Government Documents Department

H/degree/ temperature and density measurements in a Penning surface-plasma H/sup minus/ ion source

Description: Using vacuum ultraviolet laser-absorption spectroscopy, the H/degree/ density and temperature are measured as a function of discharge current and H/sub 2/-gas flow in both the plasma column and the drift region between the plasma column and the emitter in the 4X source. For typical source operating parameters, the atom temperature is 1.5 eV in the plasma column and 0.6 eV in the drift region; the atom density, 7 /times/ 10/sup 14/ cm/sup /minus/3/ in the plasma column and 4 /times/ 10/sup 14/ cm/sup /minus/3/ in the drift region. Separate measurements give 2% for the ratio of H/sub 2/ molecules in the first vibrational level to the total H/sub 2/ density. 8 refs., 6 figs., 1 tab.
Date: January 1, 1989
Creator: Smith, H.V. Jr.; Allison, P.; Pitcher, E.J.; Stevens, R.R. Jr.; Worth, G.T.; Stutzin, G.C. et al.
Partner: UNT Libraries Government Documents Department