| Paper | Title | Page |
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| MOP028 | Creation of Peaks in the Energy Spectrum of Laser-Produced Ions by Phase Rotation | 97 |
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Efficient acceleration of ions with use of very high electromagnetic field created by a high power laser has been paid attention because of its attainable very high acceleration gradient. Its intensity, however, has exponentially decreases according to the increase of its energy, which causes essential difficulty for its real application. For the quality improvement of laser-produced ions in their energy spreads, a scheme to apply an additional RF electric field synchronous to the pulse laser, called “Phase Rotation”,* has been applied to the ions produced from the thin foil target 3 and 5 mm, in thickness by irradiation of focused Ti:Sapphire laser with the wave length of 800 nm after optimization of the ion production process with use of real time observation of ion energy by TOF measurement.** Energy peaks with the spread of 7 % have been created in the energy spectrum at the positions depending on the relative phase between the pulse laser and the RF electric field. Possible application of “Phase Rotated” laser-produced ion beam is also to be discussed.
* A. Noda et al., Laser Physics, Vol. 16, No.4, pp.647-653(2006). |
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| TUP027 | Tests of Superconducting Materials in a High-Q RF Cavity | 305 |
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Superconducting rf is of increasing importance in particle accelerators. We have developed a resonant copper cavity with high quality factor and an interchangeable wall for testing superconducting materials.* A compact TE 01 mode launcher excites the azimuthally symmetric cavity mode, which allows a gap at the detachable wall and is free of surface electric fields that could cause field emission, multipactor, and rf breakdown. The shape of the cavity is tailored to focus magnetic field on the test wall, formed by a material sample. Working at X-band allows us to test small samples in a small available dewar, as well as taking advantage of available high power. We present results of cryogenic experiments conducted with this cavity. Low power tests allow characterization of the cavity parameters and their variation with temperature; high power tests allow determination of field limits for the superconducting samples. We describe our signal processing and analysis. Our experiments begin with reactor-grade niobium, followed by MgB2.
*C. Nantista et al., “Test Bed for Superconducting Materials,” presented at the 2005 Particle Accelerator Conference, Knoxville, Tennessee, May 16-20, 2005; SLAC-PUB-11246. |
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| THP086 | Mitigation of Power Loss Due to Skin Effect by Thin-Layered Film | 785 |
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| The AC current flows only on the metal surface, which is known as skin effect. The current concentration on the surface increases power loss. This results higher transmission loss of cable and degradation of Q in cavities. Skin effect on a metal film that is thinner than a skin depth is investigated starting from general derivation of skin depth on a bulk conductor. The reduction of the skin effect power loss with layered conductor films is reported and discussed. |