Generation and Propagation of an Intense Rotating Proton Beam

Dreike, P. L.; Hammer, D. A.; Sudan, R. N.; Wiley, L. G.

doi:10.1103/physrevlett.41.1328

Cited by 9 publications

(12 citation statements)

References 9 publications

(3 reference statements)

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“…A schematic of the system which approximates closely the experimental arrangement of Dreike et al [22][23][24] is shown in Fig. 2.2.…”

Section: Numerical Simulations Of Injection and Trapping Of Ion Ringsmentioning

confidence: 84%

“…Thus, it is important to minimize the axial thermal spread. For injection through a magnetic cusp, this can be achieved by arranging the ion emitting surface to coincide with a flux surface (Dreike et al [22][23][24]). Humphries [79a] has summarized some of the problems associated with the formation of proton rings.…”

Section: Fig23 Transmission Coefficient T As a Function Of (A) Nmentioning

confidence: 99%

“…For reasons explained in Section 2.9, this was not an ion ring in equilibrium but nevertheless it demonstrated that ion sources of the requisite power and charge are available. A more modest programme at Cornell is directed to the creation of partially field-reversed equilibrium ion rings (f <0.1), Dreike et al [22][23][24].…”

Section: Introduction 1historical Introductionmentioning

confidence: 99%

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Field-reversed configurations with a component of energetic particles

Finn¹,

Sudan²

1982

Nucl. Fusion

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This review is concerned with the physics of field-reversed configurations created by energetic particles of large orbits, of which the earliest example is the Astron. The Astron concept has evolved into the Ion Ring Compressor in which a low-energy ring of ions is magnetically compressed to high energy for heating the confined plasma to thermonuclear ignition. A third version is the hybrid in which field reversal is created both by plasma currents as in a θ-pinch or a spheromak and a component of energetic large orbit ions to provide heating energy as well as improved stability. This paper treats first the injection, trapping, and formation of electron and ion rings from a theoretical standpoint as well as presenting the principal experimental results. The equilibria and the characteristics of the particle orbits are discussed in some detail including conditions under which the orbits cease to be integrable and pass to a stochastic description. The theory of magnetic compression of rings and the classical transport of heat and particles of the plasma confined in the closed-poloidal-field-line region is presented. The bulk of the review is concerned with low-frequency stability of such configurations by means of a generalized energy principle for treating the large-orbit particles in the Vlasov limit. The pathology of all possible unstable modes is discussed at some length. We conclude with an exhaustive survey of microinstabilities driven by the energetic particle current for a special model and conclude that most of them are stabilized by strong gradients in density and magnetic field. A brief discussion on drift modes follows. Our present theoretical understanding of these systems, although still incomplete in some respects, nevertheless leads to the view that the promise of the very favourable features of fusion reactors based on these concepts is a sufficient impetus for their continued experimental and theoretical study.

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“…A schematic of the system which approximates closely the experimental arrangement of Dreike et al [22][23][24] is shown in Fig. 2.2.…”

Section: Numerical Simulations Of Injection and Trapping Of Ion Ringsmentioning

confidence: 84%

Section: Fig23 Transmission Coefficient T As a Function Of (A) Nmentioning

confidence: 99%

Section: Introduction 1historical Introductionmentioning

confidence: 99%

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Field-reversed configurations with a component of energetic particles

Finn¹,

Sudan²

1982

Nucl. Fusion

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“…Thermofax paper witness targets show its mean radius is 10 cm and its thickness is 6 cm. When the beam is injected into vacuum (< 10" 3 Torr), it is radially and axially dispersed on a \ m distance scale, despite the presence of surface flashover electron sources in the cusp region, as previously used, 4 indicating inadequate space-charge neutralization in the cusp.…”

mentioning

confidence: 89%

“…The proton source is an annular magnetically insulated diode, similar to one described previously. 4 Pulsed coils within the anode of the diode provide both closed magnetic-flux surfaces around the anode which insulate against electron flow and a cusplike transition to the solenoidal field, as shown in Fig. 1(b).…”

mentioning

confidence: 99%

Formation and Propagation of a Proton Ring

et al. 1981

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A magnetically self-confined ring of 430-keV protons with a field reversal on axis of 3% is formed in an 8-kG solenoid, as evidenced by propagation more than 1 m in 15-400 mTorr air or hydrogen without dispersion. Up to 83% of the proton kinetic energy is in rotation and inductive coupling of axial ring energy to azimuthal plasma current induced in air (but not hydrogen) gives reflection of >50% of the ring from a 23% mirror.PACS numbers: 52.55.Ke Magnetic field configurations in which an externally applied magnetic field is reversed by currents flowing in the plasma itself are expected to have favorable plasma confinement properties and have, therefore, attracted considerable interest for fusion reactors. The current may be carried by either low-energy plasma particles or by rings of high-energy particles. Synchrotron radiation losses by energetic electrons, the possibility of plasma heating by the energetic ions, 1 and theoretical predictions of a more stable configuration 2 have lead to field-reversal schemes with use of high-energy ions. Recent developments in intense ion-beam technology have made it possible to attempt single-pulse injection and trapping of a field-reversing proton ring in a mirror well on a time scale of 0.1-1.0 jmsec. Indeed, the transient reversal of an applied magnetic field by a rotating proton beam has recently been reported, 3 although the average axial velocity and its dispersion are too large for the beam to be trapped in a mirror well or confined in its own diamagnetic well.In this Letter we report experimental results on the formation and dynamics of a rotating proton ring, whose quality is such that particles are trapped in their own 3% diamagnetic well. To summarize, an annular ~430-keV proton beam from a magnetically insulated diode is injected through a cusplike magnetic field to form a rotating proton beam. With 70% are held together axially by their own 3% diamagnetic well as they propagate more than 1 m in an 8-kG solenoidal magnetic field. Up to 15% of the residual axial beam energy is inductively coupled to azimuthal plasma currents induced in the beam-generated plasma in air, but such currents are not observed in hydrogen. Consequently, the proton beams are more efficiently reflected from the 1.23-mirrorratio downstream mirror in air than in hydrogen, with

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Compact torus—ion ring hybrid equilibria

Turnbull

Sparks

1984

Computer Physics Communications

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Generation and Propagation of an Intense Rotating Proton Beam

Cited by 9 publications

References 9 publications

Field-reversed configurations with a component of energetic particles

Field-reversed configurations with a component of energetic particles

Formation and Propagation of a Proton Ring

Compact torus—ion ring hybrid equilibria

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