Time resolved and time integrated measurement of deuterium ion fluxes and energies in the dite tokamak, using carbon probes

Erents, S.K.; Hotston, E.S.; McCracken, G.M.; Sofield, C.J.; Shea, J.H.

doi:10.1016/0022-3115(80)90308-6

Cited by 27 publications

(6 citation statements)

References 9 publications

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“…75 to around 1. 5 e V, observed at the initial stage cannot be explained by (1), (2), (3) nor (4). The instrumental width (1) and (2) are constant, and the inherent width (3) of the C 1s level is of the order of 0.1 eV.…”

Section: Lattice-displacement and Deuterium-trapping Modelsmentioning

confidence: 83%

C 1s binding-energy shift of pyrolytic graphite bombarded by keV-deuterium ions.

Gotofp

Okada

1984

J. Nucl. Sci. Technol.

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As a basic study of plasma-wall interactions, chemical state of graphite basal face after deuterium bombardment are studied by means of X-ray photoelectron spectroscopy. As the ftuence of deuterium ions with energy of 1 or 4 keY is increased from lOu to 10 18 ions/cm 2 , the C ls line is observed to shift towards the lower binding energy at first, down to the minimum by about 0.2 eV and then towards the higher energy up to an asymptotic value of about 0.2 eV higher than the initial position. The first negative shift is due to lattice displacement at the target surface, and the subsequent positive shift is due to the deuterium trapping at the graphite surface. The fluence dependence of the observed C ls shift is explained by a simple saturation model.

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Section: Lattice-displacement and Deuterium-trapping Modelsmentioning

confidence: 83%

C 1s binding-energy shift of pyrolytic graphite bombarded by keV-deuterium ions.

Gotofp

Okada

1984

J. Nucl. Sci. Technol.

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“…The probe measurements presented in Section 3 already indicate that energetic ions reach the LCFS. However, high ion energies, even outside the LCFS, have been measured in the plasma boundaries of tokamaks over a period of many years, using a variety of techniques [6][7][8][9][10][11][12][13][14][15][16]. Most of the early results remained unexplained because no ion temperature profiles inside the LCFS were available.…”

Section: Escape Of Energetic Particlesmentioning

confidence: 99%

“…In reactor conditions, the existence of pedestals with Tj(a) > 7 keV can lead to a substantial increase in confined alpha particle power and a corresponding reduction of the ignition threshold, despite prompt losses from the periphery. In the temperature range of interest, the pedestal contribution to the power of confined alphas, P ac , is <P 2 D> P ed -p 2 D ( r p ) -V l 0 S S / V (9) where p D is the the fuel pressure and V, oss is the volume from which alpha particles are lost promptly or without significant thermalization. For an ITER sized device [52], V ioss /V = 0.3 can be expected.…”

Section: Pedestal Contribution To Fusion Performancementioning

confidence: 99%

“…The calorimetrically measured heat flux to the limiters could only be explained if the ion temperatures at the LCFS were substantially higher than the local electron temperature and comparable to spectroscopically measured ion temperatures in the vicinity of the LCFS [4,5]. Evidence of ions with energies well above the local electron temperature in the SOL, obtained with various probe techniques has been available for a long time [6][7][8][9][10][11][12][13][14][15][16]. However, only recent spectroscopic measurements inside the LCFS have shown that the boundary ion temperatures are sufficiently high to explain the probe results in terms of particles escaping from the thermal population just inside the LCFS.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Boundary ion temperatures and ion orbit losses in JET

Weisen¹,

Bergsåker²,

Campbell

et al. 1991

Nucl. Fusion

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Ion and electron temperatures of up to 5 keV have been obtained within 10 cm of the last closed flux surface (LCFS) in hot ion H-modes with 18 MW of neutral beam heating. The ion temperature profiles appear to have ‘pedestals’ which scale with power per particle, Ti(a) ⪅ P(a)/ne(0.9a) [keV, MW/1019 m−3], in H-modes. In L-modes the pedestal temperatures are an order of magnitude lower. This difference can be explained by the one order of magnitude difference in particle residence time in the two confinement modes. In H-modes, the resulting pressure ‘pedestals’ contribute typically 40% (up to 5 MJ) to the plasma stored energy, accounting for about half of the confinement improvement compared with the L-mode. The remaining improvement occurs across the entire plasma, but most notably in the periphery. There is ample evidence that ions with energies in the keV range escape to and beyond the LCFS and account for most of the loss power in the ion channel. This evidence includes results from energy discriminating probes in the scrape-off layer and the analysis of the characteristics of the heat strike zones in the X-point configuration. The observed boundary ion temperatures have far reaching implications for fusion reactivity, power handling, wall erosion and impurity production in reactor conditions. They suggest that it is possible to bring the entire volume of a reactor plasma to thermonuclear temperatures, with a considerable boost to the overall thermonuclear reactivity.

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“…The Langmuir probe measurements are supported by direct measurements of deuteron flux using a rotating carbon collection probe [13,14] as shown in Fig. 2.…”

mentioning

confidence: 91%