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Neutral and plasma density have been measured in the north well of the central cell of the Tara tandem mirror [Nucl. Fusion 22, 549 (1982)]. The electron plasma density and temperature on the magnetic axis were measured by Thomson scattering to be about 3×1012 cm−3 and 70 eV, respectively. The corresponding axial neutral hydrogen density was found to be 1 ×109 cm−3, while near the plasma edge at r=15 cm it reached 1×1010 cm−3. The fill gas density at r≥22.5 cm was ≊1011 cm−3. Additional information from secondary electron detectors was used to estimate the radial ion temperature distribution, which was found to have about the same width, 12 cm, as the plasma density. The resulting ion pressure profile is peaked compared to the electron pressure profile. Charge exchange losses in the well are found to have a maximum at a radius equal to half the e‐folding distance of the plasma density and ion temperature distributions.

An attempt was made to detect neutrons from the so-called cold nuclear fusion of deuterium in palladium and titanium, both saturated with deuterium: the palladium electrolytically and the titanium from gas phase. The measurements were performed in a tunnel located 30 m deep in limestone, using3He filled proportional counters surrounded by water for neutron moderation. In all cases the detected neutron flux was practically equal to the background level. Very low upper limits to the neutron source strength were obtained from this experiment: 2×10−4 n.s−1g−1 Pd and 4.3×10−4 n.s−1g−1 Ti on the 1 level.

Ten samples prepared from different kinds of metallic glasses (differing in composition and manufacturing technology) were bombarded by 2 or 1 MeV helium ions with high fluence under different experimental conditions. During bombardment the sample temperature rise caused by irradiation heating was estimated and kept below the temperature that is needed for the investigated metallic glass to crystallize. In all cases the surface deformation processes were dominated by flaking, i.e. nearly from the whole implanted area a layer of uniform thickness corresponding to the applied ion projected range suddenly flaked off. The surface left behind the flaked layer was characterized by a wave-like structure, i.e. by a regular series of asymmetrical elevations. Such periodical elevations which did not appear on the annealed samples are caused by a mechanism developed during the bombardment of the amorphous structure (of metallic glasses) by high energy helium ions. Details of this outstanding phenomena are discussed.

The mechanism of blister formation on a cold-rolled gold target by 3.52 MeV helium ion bombardment was investigated. The critical dose was found to be 6 × 10 17 He + /cm 2 under the experimental condition used. To study the inner morphology of the blisters, they were opened mechanically. Based on these observations several new features are reported. A speculative model of high-energy blister formation is discussed, based on the fact that the diameter increases in discontinuous steps. It is pointed out that in MeV energy region this formation could be exfoliation rather than blistering confirming the previous investigations.

This paper presents recoil cross sections for both H and D for alpha particle bombardment in the energy range of 1.6 to 3.4 MeV. For hydrogen and deuterium, a non-Rutherford cross-section was found. For deuterium, a resonance at 2.15 MeV with fwhm of 75 keV was obtained. Calculations were carried out to find the geometrical arrangement where the maximum information concerning the probing depth can be obtained in the energy range of 1–10 MeV. In contrast to the generally accepted 30° scattering angle, another configuration is suggested.

During MeV 14 N + backscattering analysis to detect sub-monolayer heavy impurities, a “beam effect”, i.e. high impurity loss was found. To clarify the situation a systematic study was done on gold films in the thickness range of 0.5–3200 atom/nm 2 evaporated onto silicon. Results suggest that sputtering of cascades induced by energetic nitrogen ions is responsible for the phenomenon. The sputtering yield of gold was a linear function of surface coverage in the range of 0.5–130 atom/nm 2 . For thick overlayers (⩾ 800 atom/nm 2 ) a saturation value of S ≊ 0.8 gold/N + was found. Between these two regions intermediate behavior was experienced. A rough theoretical model is outlined for overlayer sputtering in the MeV energy region.

Ten different samples of metallic glasses were bombarded by 2- or 1-MeV helium ions. The sample temperature was kept below the crystallization temperature. Surface-deformation processes were dominated by flaking, i.e., from nearly the whole implanted area a layer flaked off with a uniform thickness corresponding to the ion range. The surface remaining behind the flaked layer showed a characteristic pattern. Such a periodic pattern did not appear on the annealed samples.

The Tara Tandem Mirror has a 10 m long, 22 cm diameter central cell plasma heated by fundamental ion cyclotron heating. Typical central cell parameters in unplugged operation are n = 3 × 1012/cm3, Ti⊥ = 300 eV, Ti∥ ≃ 75 eV. The axisymmetric plug cell incorporates sloshing ions and ECH to generate axial confining potentials. The axisymmetric central cell and plug comprise a max B mirror which is observed to operate in both flute stable and unstable regimes. The flute instability is m = 1 and can be stabilized by an outboard anchor. The anchor plasma is formed by electron and ion cyclotron heating. Satisfactory operation of a tandem mirror requires extensive control of neutral gas from neutral beam (NB) sources [1] and startup. Tara makes extensive use of Ti gettering in the beamlines, beam dumps and plasma surfaces for both hydrogen pumping and reflux control. A description of this technology along with its impact on plasma performance is discussed.

In order to try and outline the energy dependence of surface deformations such as exfoliation and flaking on candidate CTR first-wall materials, stainless steel and two types of inconels were bombarded by 0.8, 1 and 4 MeV helium ions. All the bombarded spots could be characterized by large exfoliations covering almost the total implanted area. No spontaneous rupture was observed except on one type of inconel where flaking took place right after reaching the critical dose. After mechanical opening of the formations, similar inner morphology was found as in our previous studies on gold [5,6].

Surface deformations on both amorphous and polycrystalline alloys of METGLASS 2826A caused by high dose bombardment of helium ions of energy 2 and 3.52 MeV were examined by RBS analysis and SEM. Both observations confirm that the resistance of the amorphous form against flaking is 70% higher. The morphology of the metallic glass surface after flaking is characterized by a wave-like structure. For higher energy bombardment and higher current density the surface deformations are characterized by competition of two processes, i.e. exfoliation and flaking presumably due to temperature effects.

Single crystal silicon wafer covered by Al foil of thickness 5 μm was irradiated quasi-simultaneously by multiple-energy He ions up to the fluence level of 3.3 × 10 19 ions/cm2. The implantation was performed by 3.5 MeV 4He+ through a moving Al absorber foil in such a way that a nearly uniform He distribution was obtained extending in both Si and Al to depth intervals of 1.9 × 10 19 Si/cm2 and of 1.5 × 10 19 Al/cm2, respectively. During irradiation the evolution of the He concentration-depth profile was studied in situ by 3 MeV proton RBS analysis. It was found that the He concentration in the Al cover foil, after reaching a maximum value of 30 at.% began to decrease. This accelerated re-emission process was initiated near the inter-boundary surface and extended inward gradually. No significant He escape was observed from the Si up to the applied dose, so at the end of the implantation a He concentraton of 80 at.% has been reached. Exposing both inter-boundary surfaces to SEM, flaking from numerous spots was observed on the Al but not on the Si where only one crater was found. After mechanically breaking the implanted Si wafer and Al cover foil it could be seen on the fracture surfaces that regions containing a large amount of He acquire a sponge-like structure. Channels and large cavities were also observed in this region of the broken Si produced as cracks of interconnected He bubbles. The appearance of the flaking processes clearly demonstrates that even with such a depth distribution the He implanted in the materials in spite of re-emission may reach the critical value for blistering or flaking. The critical concentrations required for the observed surface deformation together with the thickness of the flaked layers evaluated from RBS and SEM observations are discussed.

The values of the rotation angles for the 298 keV and 360 keV states of103Rh measured after Coulomb-excitation with 2.5 MeV protons in Fe51.5 Rh48.5 alloy are interpreted by considering the existence of a transient field at such low energies, too.

The proton polarization predicted by an approximate form of the weakly bound projectile (WBP) model for (d, p) reactions is compared with measured polarization. Qualitative fits are obtained, using the same set of parameters which previously gave good fits to the magnitude and shape of six selected angular distributions. It is shown that the main features of the proton polarization arise from the proton-target nucleus scattering. In most cases studied, the polarization is essentially identical to the elastic scattering polarization, as previously indicated by Pearson and Coz. The agreement between the observed and predicted polarization supports their basic physical picture.

The g -factor of the 633 keV 2 + K = 2 γ-vibrational state in 188 Os was measured with the use of an internal magnetic field and found to be 0.39±0.12. The known values of the g -factor of the 155 keV 2 + K = 0 state and of the E2-M1 mixing parameter of the 478 keV radiation permitted the evaluation of the ratio of the strength of pairing forces for protons to that for neutrons as G p / G n = 1.53±0.02.

The g factors of the 316 keV 2+ state in 192Pt, the 329 keV 2+ and the 622 keV 2+ states in 194Pt have been investigated by measuring the rotation of the angular correlation patterns in the internal field at the nucleus in FeIr alloy. The results are 0.24±0.05, 0.21±0.03 and 0.131±0.03, respectively. For the 206 keV 2+ state in 192Os the value of ωτ is found to be 0.235±0.034. The internal field is, however, not known in Os and a reliable value of the g factor cannot be derived. The values of the g factors in Pt do not agree with the predictions of the phenomenological theory of vibration.

A laser fluorescence diagnostic has been used for measuring the neutral hydrogen density in the central cell of the Tara thermal barrier tandem mirror. Experiments have been performed using laser‐induced, resonance fluorescence detection of Hα (6563‐A) radiation. Measurements were made at a number of radial positions with 1‐cm resolution, from the magnetic axis to near the plasma limiter. Stray laser light contributions to the signal were eliminated with a double‐pulse technique. For comparison, the chord‐averaged plasma Hα radiation was analyzed under the identical conditions for which laser fluorescence data were taken.

The energy dependence of surface deformation for high dose helium implantation in the energy range of 1-3.52 MeV is reported. Based on the observations, it is suggested that exfoliation for high energy irradiation is the result of blister coalescence. Besides the transition energy between exfoliation and blistering is close to 1 MeV.

The precession in the internal field of the angular correlation pattern of the 675 kev--412 kev cascade of Hg/sup 198/ following BETA -decay of Au/sup 198/ was measured to determine the g-factor of the 412-kev state. g was found to be +0.38 plus or minus 0.68. (R.E.U.)

The values of the rotation angles for the 298 keV and 362 keV states of 103Rh, measured after Coulomb excitation with 2.5 MeV protons in Fe51.5Rh48.5 alloy, are interpreted by considering the existence of a transient field even at such low energies.