Energetic Plasma Losses Due to Microinstabilities

Dunlap, J. L.; Haste, G. R.; Postma, H.; Reber, L.H.

doi:10.1103/physrevlett.14.937

Cited by 3 publications

(3 citation statements)

References 9 publications

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“…For pellet fusion p would include neutron energy losses (and Q = Qn + Q+)-A set of coupled particle conservation equations must also be included. Table I gives experimental results from the MIT ALCATOR [14], the ORNL ORMAK [15], the Kurchatov T-10 [16], the Princeton PLT [17], the Fontenay-aux-Roses TFR [18], the LLL 2XII-B [19], the ORNL DCX-1 [20], and the FEC MIGMA [21]. The present status of plasma experiments is clearly far short of ignition feasibility, whether measured by direct comparison of the f value, i.e.…”

Section: + P Extmentioning

confidence: 99%

Interaction of neutrons at high energies

Lyubimov¹

1977

Sov. Phys. Usp.

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This paper presents some novel interpretations of fusion plasmas which may be of interest to both fission and fusion scientists and engineers. A new fusion ignition parameter (Tn e r E )i is proposed which is proportional to 0 2 B 4 and inversely proportional to the fusion power density (PFusion) °f a reacting plasma. Curves are given for many potential nuclear fusion fuels. The energy utilization factor in existing devices is defined as f = PFusion/PLoss = (Tn e TL)/(Tn e TE)i; in experimental plasmas, f has increased by about two orders of magnitude in the past decade and now exceeds 10" 4 (a "nearest" f* exceeds 10~3). The f factor is also analogous to its fission counterpart in the four-factor neutron multiplication factor k = f rj e p, where f is the neutron thermal utilization factor. Past, present, and future fusion experiments are discussed briefly in this context.

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Section: + P Extmentioning

confidence: 99%

Interaction of neutrons at high energies

Lyubimov¹

1977

Sov. Phys. Usp.

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“…1 " 3 Microinstabilities are capable of producing hot-ion losses, 4 and therefore are a major threat to progress in generation and confinement of thermonuclear plasmas in many of the present experiments. Since the design of future experiments presumably will rely heavily upon microinstability theory, experimental studies of microinstabilities are of particular importance when the results can be identified with predictions of theory.…”

mentioning

confidence: 99%

“…8 We write l /a 2 F\ T.V •(f), -at + Pp f2 + ytp' + 6t 2 , (4) and by development exactly analogous to that of Landau 6 (see also Ref. 5) we obtain, after some algebra, '"-#* w$-m"-<• > where the negative sign is for the vapor and the positive one for the liquid.…”

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confidence: 99%

Observation of Negative-Mass Instability in an Energetic Proton Plasma

et al. 1966

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Microinstabilities at and above ion gyrofrequency are present in almost all hot ion plasmas, even those stabilized against hydromagnetic instabilities by magnetic wells. 1 " 3 Microinstabilities are capable of producing hot-ion losses, 4 and therefore are a major threat to progress in generation and confinement of thermonuclear plasmas in many of the present experiments. Since the design of future experiments presumably will rely heavily upon microinstability theory, experimental studies of microinstabilities are of particular importance when the results can be identified with predictions of theory.In this Letter we briefly describe experimentally observed threshold properties of a microinstability in an energetic proton plasma, and we identify these properties with those of a theoretically recognized instability. We have measured the threshold density and instability growth times for a "standard" proton distribution (to be described), and the response of threshold to changes in (1) the magnetic field shape, (2) the energy spread of trapped protons, and (3) the proton distribution in radial oscillation amplitude. We have also measured the dependence of the fundamental mode frequency on changes in radial oscillation amplitude. We show that the observed properties are those of the negative-mass instability 5 ' 6 familiar from accelerator experience, and we exclude interpretation in terms of the driftcyclotron instability, 7 " 9 the other likely candidate. 4 ' 10 A detailed report of these studies is in preparation.The plasma is created in the DCX-1 facility by dissociation of 600-keV H 2 + injected into a magnetic mirror field with a central field value of 10 kG. The experimental instability is the "gyrofrequency mode" of earlier papers. 4 ' 10 It is characterized by reception on electrostatic and magnetic (B z polarization) probes of rf signals near harmonics of the ion gyrofrequency. Descriptions of the experimental facility, details of the proton losses associated with this mode under certain operating conditions, data on the rf spectrum, and previous considerations of mode assignment for this instability are given in the earlier papers.The gyrofrequency mode of instability can be isolated from other unstable modes of this plasma by using gas-collisional dissociation of the molecular-ion beam at fairly high gas pressures (of order 10" 6 Torr), and this was done in these experiments. Helium was used as the background gas, and trapped-proton lifetimes for most of the experiments were 50-75 jusec.The threshold measurements were made in the period of rising density just after the molecular ion beam was turned on. For the energy-spreading experiments, the measurements were also made in steady state, with the density controlled by varying the beam current. For the threshold density, we take values inferred from measurements of the escaping charge-exchange neutrals at the time of first appearance of the rf signals.The "standard" plasma distribution is that established using the normal plasma radius (20 cm) and H 2 + be...

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Plasma Production by Molecular Ion Injection into a Magnetic Mirror Supplemented with a Radio Frequency Electric Field

Akimune¹

1971

The Physics of Fluids

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Energetic Plasma Losses Due to Microinstabilities

Cited by 3 publications

References 9 publications

Interaction of neutrons at high energies

Interaction of neutrons at high energies

Observation of Negative-Mass Instability in an Energetic Proton Plasma

Plasma Production by Molecular Ion Injection into a Magnetic Mirror Supplemented with a Radio Frequency Electric Field

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