Broad-Range Magnetic Spectrograph

Browne, C.P.; Buechner, W. W.

doi:10.1063/1.1715411

Cited by 202 publications

(42 citation statements)

References 3 publications

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“…where L L R = , x x R = , and ỹ y R = , and can be derived using the same procedure as in the original Browne-Buechner paper [29], but without assuming R=L. The effect of increasing L relative to R is to move the focal plane closer to the magnetic field boundary and to decrease the slope.…”

Section: Resultsmentioning

confidence: 99%

Experimental and theoretical investigations of a 17GHz RF gun

Brown

Trotz

Kreischer

et al. 1999

Nuclear Instruments and Methods in Physics Research Section A:

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We report on experimental and theoretical investigations of a 17 GHz RF photocathode electron gun. This is the first photocathode electron gun to operate at a frequency above 2.856 GHz. The 1.5 cell, π−mode, copper cavity was tested with 50 ns pulses from a 17.150 GHz klystron amplifier built by Haimson Research Corp. A Bragg filter was used at the RF gun to reduce the reflection of parasitic modes back into the klystron. Coupling hole theory in conjunction with cold test measurements was used to determine the field profile in the RF gun. The particle in cell code MAGIC as well as coupled envelope equations were used to simulate the beam dynamics in the RF gun. With power levels of 4 MW, the on axis electric field at the cathode exceeds 300 MV/m, corresponding to an average accelerating gradient of 200 MV/m over the first half cell of the gun. Breakdown was observed at power levels above 5 MW. Electron bunches were produced by 20 µJ, 1 ps UV laser pulses impinging on the RF gun copper photocathode and were measured with a Faraday cup to have up to 0.1 nC of charge. This corresponds to a peak current of about 100 A, and a density at the cathode of 8.8 kA/cm 2 . Multiple output electron bunches were obtained for multiple laser pulses incident on the cathode. Phase scans of laser induced electron emission reveal an overall phase stability of better than ±20°, corresponding to ±3 ps synchronization of the laser pulses to the phase of the microwave field. A Browne-Buechner magnetic spectrometer indicated that the RF gun generated 1MeV electrons with a single shot rms energy spread of less than 2.5%, in good agreement with theoretical predictions.3

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Section: Resultsmentioning

confidence: 99%

Experimental and theoretical investigations of a 17GHz RF gun

Brown

Trotz

Kreischer

et al. 1999

Nuclear Instruments and Methods in Physics Research Section A:

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“…The ALPHA-X spectrometer features a Browne-Buechner design 25 to provide strong focusing in the horizontal and vertical planes thus enabling excellent energy resolution to be maintained over a wide energy range (from < 1% at the lower energy end to ~10% at the upper end). Scintillating Ce:YAG crystals positioned at the focal plane are used to image electrons exiting the spectrometer field and the image is captured on a 12-bit CCD camera.…”

Section: Methodsmentioning

confidence: 99%

Narrow spread electron beams from a laser-plasma wakefield accelerator

et al. 2009

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The Advanced Laser-Plasma High-Energy Accelerators towards X-rays (ALPHA-X) programme is developing laser-plasma accelerators for the production of ultra-short electron bunches with subsequent generation of incoherent radiation pulses from plasma and coherent short-wavelength radiation pulses from a free-electron laser (FEL). The first quantitative measurements of the electron energy spectra have been made on the University of Strathclyde ALPHA-X wakefield acceleration beam line. A high peak power laser pulse (energy 900 mJ, duration 35 fs) is focused into a gas jet (nozzle length 2 mm) using an F/16 spherical mirror. Electrons from the laser-induced plasma are self-injected into the accelerating potential of the plasma density wake behind the laser pulse. Electron beams emitted from the plasma have been imaged downstream using a series of Lanex screens positioned along the beam line axis and the divergence of the electron beam has been measured to be typically in the range 1-3 mrad. Measurements of the electron energy spectrum, obtained using the ALPHA-X high resolution magnetic dipole spectrometer, are presented. The maximum central energy of the monoenergetic beam is 90 MeV and r.m.s. relative energy spreads as low as 0.8% are measured. The mean central energy is 82 MeV and mean relative energy spread is 1.1 A theoretical analysis of this unexpectedly high electron beam quality is presented and the potential impact on the viability of FELs driven by electron beams from laser wakefield accelerators is examined

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“…; she result is However, by using the firstorder focusing condition to eliminate e. from the defining equation for the magnification, one can show the equivalence of the two proposed equations for the magnification. The relative spread in momentum (denoted by Ap/p « Ap/p) can be obtained by rewriting the expression for W, 9 where /., «., J& 2 , e«, p, and q> ar® related by the firstorder focusing condition. The result is FocalSurface Geometry…”

Section: B the Magnet Design I Xon Opticsmentioning

confidence: 99%

“…If the flat ends of the two mating halves of the scattering chamber ware merely butted together, the frictionsI drag during rotation under vacuum would be enormous and would tend to gall the mating surfaces. In order to reduce this sliding friction, the flat surfaces of the mating ends of The stationary cylinder of the scattering chamber contains the incident-beam port, the beam-monitoring flap (a miniature Faraday cup), the target-wheel assembly, the target-menltorlng-detector ports 9 and the thermocouple and ion gauges. Machinist's Drawing of Collimator I « 1 cos T^ cos Cj ♦ J cos Tl sin Cj * k sin Tl ,…”

Section: Tha Suspensionmentioning

confidence: 99%