Beam loading compensation in the NLCTA

Adolphsen, C.; Lavine, T. L.; Nantista, C.; Ruth, R.; Wang, J.; Yeremian, D.

doi:10.1109/pac.1997.750798

Cited by 8 publications

(10 citation statements)

References 6 publications

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“…The gradient in the two 0.9 m traveling wave sections should be about 50 MeV/m including the beam loading compensation. Beam loading compensation is accomplished by introducing a ramp in the leading 50 ns of the RF pulse until the beam loading reaches a steady state [5]. The plan is to condition the injector system to operate with 90 MW, 225 ns, RF power available to each of the 0.9 m accelerating sections.…”

Section: Beamline Setupmentioning

confidence: 99%

“…The energy and energy spread of the beam are measured with the profile monitor in the high dispersion region of the chicane and the emittance of the beam is measured using quad scans and a screen upstream and downstream of the chicane [8]. Bunch to bunch energy and energy spread variations are measured at the end of the machine close to the final dump using a pulsed bend magnet with a ramped current to sweep the bunch train vertically for the duration of the pulse, while a DC bend magnet bends the bunches in the horizontal plane allowing the measurement of the energy spread, from the head to the tail of the train [5]. A bunch length monitor [4,9] after the first accelerator section is used to set the power and phase of the two prebunchers with respect to the first accelerator section for optimum bunching.…”

Section: Vacuum Valvementioning

confidence: 99%

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NLCTA injector experimental results

Yeremian

Adolphsen

Miller

et al.

Proceedings of the 1997 Particle Accelerator Conference (Cat. No.97CH36167)

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The purpose of the Next Linear Collider Test Accelerator (NLCTA) at SLAC is to integrate the new technologies of X-band accelerator structures and RF systems for the Next Linear Collider (NLC), demonstrate multibunch beam-loading energy compensation and suppression of higher-order deflecting modes, measure the transverse components of the accelerating field, and measure the dark current generated by RF field emission in the accelerator [1]. For beam loading R&D, an average current of about 1 A in a 120 ns long bunch train is required. The initial commissioning of the NLCTA injector, as well as the rest of the accelerator have been progressing very well. The initial beam parameters are very close to the requirement and we expect that injector will meet the specified requirements by the end of this summer.

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Section: Beamline Setupmentioning

confidence: 99%

Section: Vacuum Valvementioning

confidence: 99%

NLCTA injector experimental results

Yeremian

Adolphsen

Miller

et al.

Proceedings of the 1997 Particle Accelerator Conference (Cat. No.97CH36167)

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“…The phase modulation is eventually converted, by a high-power pulse compression system (SLED-II, described by Tantawi et al, in these proceedings [5]) to amplitude modulation which compensates for transient beam loading in the accelerator (see Adolphsen et al, in these proceedings [6]). Figure 2 shows an example of a phase profile and the predicted RF amplitude waveform that results after highpower RF pulse compression.…”

Section: Phase Profilesmentioning

confidence: 99%

Low-level RF signal processing for the Next Linear Collider Test Accelerator

Holmes

Ziomek

Adolphsen

et al.

Proceedings of the 1997 Particle Accelerator Conference (Cat. No.97CH36167)

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In the X-band accelerator system for the Next Linear Collider Test Accelerator (NLCTA), the Low Level RF (LLRF) drive system must be very phase stable, but concurrently, be very phase agile. Phase agility is needed to make the Stanford Linear Doubler (SLED) power multiplier systems Energy work and to shape the RF waveforms to compensate beam loading in the accelerator sections. Similarly, precision fast phase and amplitude monitors are required to view, track, and feed back on RF signals at various locations throughout the system. The LLRF is composed of several subsystems: the RF Reference System generates and distributes a reference 11.424GHz signal to all of the RF stations, the Signal Processing Chassis creates the RF waveforms with the appropriate phase modulation, and the Phase Detector Assembly measures the amplitude and phase of monitored RF signals. The LLRF is run via VXI instrumentation. These instruments are controlled using HP VEE graphical programming software. Programs have been developed to shape the RF waveform, calibrate the phase modulators and demodulators, and display the measured waveforms. This paper describes these and other components of the LLRF system.

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“…A beam . loading compensation scheme [3] is used to achieve uniform acceleration in the structures, minimizing energy variation along the pulse as it travels through the steering and focusing lattice.…”

Section: Introductionmentioning

confidence: 99%

Beam current monitors in the NLCTA

Nantista

Adolphsen²

Proceedings of the 1997 Particle Accelerator Conference (Cat. No.97CH36167)

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The current profile along the 126 ns, multi-bunch beam pulse in the Next Linear Collider Test Accelerator (NLCTA) is monitored with fast toroids (rise time -1 ns). Inserted at several positions along the beam line, they allow us to track current transmission as a function of position along the bunch train. Various measurements, such as rise time, current, width, and slope, are made on the digitized signals, which can be corrected in software by means of stored frequency response files. The design and implementation of these devices is described.

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Beam loading compensation in the NLCTA

Cited by 8 publications

References 6 publications

NLCTA injector experimental results

NLCTA injector experimental results

Low-level RF signal processing for the Next Linear Collider Test Accelerator

Beam current monitors in the NLCTA

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