The Single Pass RF Driver: Final beam compression

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• 作者：Robert Burke
• 关键词：Fusion ; Inertial confinement fusion (ICF) ; Heavy ion fusion (HIF) ; Radiofrequency HIF Driver ; Cylindrical ICF pellet ; Fusion energy ; Fusion energy economics
• 刊名：Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment
• 出版年：1 January, 2014
• 年：2014
• 卷：733
• 期：Complete
• 页码：158-167
• 全文大小：2250 K

文摘

The Single Pass RF Driver (SPRFD) compacts the beam from the linac without storage rings by manipulations that take advantage of the multiplicity of isotopes (16), the preserved 碌bunch structure, and increased total linac current. Magnetic switches on a first set of delay lines rearrange the internal structure of the various isotopic beams. A second set of delay lines sets the relative timing of the 16 isotopic beam sections so they will telescope at the pellet, in one of multiple fusion chambers, e.g. 10.

Shortening each isotopic beam section uses preservation of the 碌bunch structure up to the final ~2 km drift before final focus. Just before the final drift, differential acceleration of the 碌bunches in each isotopic beam section (128 total) launches an axial collapse, referred to as the 鈥淪lick鈥? The 碌bunches interpenetrate as their centers of mass move toward each other and individual 碌bunches lengthen due to their momentum spread. In longitudinal phase space they slide over one another as they lengthen in time and slim down in instantaneous energy spread.

The permissible amount of 碌bunch lengthening is set by the design pulse shape at the pellet, which varies for different groups of isotopes. In narrow bands of ranges according to the role for each isotope group in the pellet, the ranges extend from 1 to 10 g/cm² to drive the cylinder barrel and thin hemispherical end caps, to heat the ~0.5 g/cm² 蟻R fast ignition zone, and to improve the quasi-sphericity of the compression of the fast ignition zones at the pellet's ends.

Because the 碌bunch-碌bunch momentum differences are correlated, time-ramped beamline transport elements close after the differential accelerator are used to correct the associated shifts of focal point. Beam neutralization is needed after the differential acceleration until adjacent bunches begin to overlap. Concurrent collapse of each isotope and telescoping of the 16 isotopes cause the current in each beamline to rise rapidly during the final microsecond of driver pulse generation.

Principal topics discussed are some basic considerations for the final compression processes, benefits for pellet implosion and ignition that may result from new means to shape the power deposition in the pellet in 3D and in time, and immediate needs for investigations. Economics that use HIF's potential for large economies of scale are summarized, to establish the reality of a large fusion energy complex achieving a high share of the overall benefits of fusion: abundance, cleanliness, safety, affordability, and profits.