Multilayer high gradient insulator technology

Sampayan, S.; Vitello, P.; Krogh, M.; Elizondo, J.M.

doi:10.1109/94.848910

Cited by 39 publications

(12 citation statements)

References 16 publications

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“…Some prospects for producing compact designs include laser-induced plasma wakefield accelerators, 4,5 miniaturized cyclotrons, 6 and the dielectric wall accelerator ͑DWA͒. 7 Of paramount importance to the design of all of these accelerators is the maximum proton kinetic energy that must be achieved. Higher proton energies lead to increased volume of the apparatus, increased magnet current for beam transport, and increased cost of the entire facility due to neutron shielding.…”

Section: Introductionmentioning

confidence: 99%

Maximum proton kinetic energy and patient‐generated neutron fluence considerations in proton beam arc delivery radiation therapy

et al. 2009

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Several compact proton accelerator systems for use in proton therapy have recently been proposed. Of paramount importance to the development of such an accelerator system is the maximum kinetic energy of protons, immediately prior to entry into the patient, that must be reached by the treatment system. The commonly used value for the maximum kinetic energy required for a medical proton accelerator is 250 MeV, but it has not been demonstrated that this energy is indeed necessary to treat all or most patients eligible for proton therapy. This article quantifies the maximum kinetic energy of protons, immediately prior to entry into the patient, necessary to treat a given percentage of patients with rotational proton therapy, and examines the impact of this energy threshold on the cost and feasibility of a compact, gantry-mounted proton accelerator treatment system. One hundred randomized treatment plans from patients treated with IMRT were analyzed. The maximum radiological pathlength from the surface of the patient to the distal edge of the treatment volume was obtained for 180°continuous arc proton therapy and for 180°split arc proton therapy ͑two 90°arcs͒ using CT# profiles from the Pinnacle™ ͑Philips Medical Systems, Madison, WI͒ treatment planning system. In each case, the maximum kinetic energy of protons, immediately prior to entry into the patient, that would be necessary to treat the patient was calculated using proton range tables for various media. In addition, Monte Carlo simulations were performed to quantify neutron production in a water phantom representing a patient as a function of the maximum proton kinetic energy achievable by a proton treatment system. Protons with a kinetic energy of 240 MeV, immediately prior to entry into the patient, were needed to treat 100% of patients in this study. However, it was shown that 90% of patients could be treated at 198 MeV, and 95% of patients could be treated at 207 MeV. Decreasing the proton kinetic energy from 250 to 200 MeV decreases the total neutron energy fluence produced by stopping a monoenergetic pencil beam in a water phantom by a factor of 2.3. It is possible to significantly lower the requirements on the maximum kinetic energy of a compact proton accelerator if the ability to treat a small percentage of patients with rotational therapy is sacrificed. This decrease in maximum kinetic energy, along with the corresponding decrease in neutron production, could lower the cost and ease the engineering constraints on a compact proton accelerator treatment facility.

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Section: Introductionmentioning

confidence: 99%

Maximum proton kinetic energy and patient‐generated neutron fluence considerations in proton beam arc delivery radiation therapy

et al. 2009

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“…As with conventional insulators 8 , HGIs are able to withstand higher gradients as the duration of the applied voltage decreases 16,19,23 . We are currently developing a compact accelerator for proton radiotherapy which will take advantage of this effect 4 .…”

Section: Displacement Current Effectsmentioning

confidence: 99%

“…Conditioning was not observed by Sampayan in structures formed from silica with sputtered gold electrodes 19 . All of these tests were conducted with pulsed voltages, with pulse lengths varying from about 20 ns to about 2 µs.…”

Section: A Testing Procedures and Conditioningmentioning

confidence: 99%

Vacuum insulator development for the dielectric wall accelerator

Harris

Blackfield

Caporaso

et al. 2008

Journal of Applied Physics

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At Lawrence Livermore National Laboratory, we are developing a new type of accelerator, known as a Dielectric Wall Accelerator, in which compact pulse forming lines directly apply an accelerating field to the beam through an insulating vacuum boundary. The electrical strength of this insulator may define the maximum gradient achievable in these machines. To increase the system gradient, we are using "High Gradient Insulators" composed of alternating layers of dielectric and metal for the vacuum insulator. In this paper, we present our recent results from experiment and simulation, including the first test of a High Gradient Insulator in a functioning Dielectric Wall Accelerator cell. a) Electronic mail: harris89@llnl.gov 2

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“…There is interest in this type of insulator for particle accelerator applications because it could possibly enable higher field gradients and also be in close proximity to the beam line, which has advantages for power flow impedance matching and suppression of beam-breakup instabilities [6]. Although testing has been done to evaluate performance levels and determine scaling for various structures, the exact mechanism that may be governing performance is not yet fully understood [7]. The work we have done was to add secondary electron emission physics to an existing PIC (particle-incell) code to study the effect of the secondary electron avalanche on conventional insulators can be expanded to study the underlying mechanism of voltage hold off of the so-called high gradient insulators.…”

Section: Introduction/backgroundmentioning

confidence: 99%