Noncryogenic pellet injector for diagnostic purposes on the RFX reversed field pinch

Garzotti, L.; Innocente, P.; Martini, S.; Reggiori, A.; Daminelli, Giambattista

doi:10.1063/1.1149290

Cited by 7 publications

(7 citation statements)

References 7 publications

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“…Lithium wall conditioning in RFX-mod was performed by injecting lithium pellets during plasma discharges. For this purpose a room temperature pellet injector (RTPI) was used [21]. RTPI allows injection of pellets of any solid material at room temperature with sizes from 0.1 mm up to 4.5 mm.…”

Section: Lithium Pellet Injection Techniquementioning

confidence: 99%

“…Compared with the clean graphite case, after lithization the density increase is lower for the same amount of gas; furthermore, the HeGDC used for density control is performed when there is a large number of wall trapped particles and when the plasma density is still low (figure 5). Indeed with clean graphite the density can be controlled up to a total number of about (1-2)×10 21 filled particles, whereas after the lithization it can be controlled up to a total number of about (4-5) × 10 21 filled particles. The lithium absorbing effect is slightly better than that of boron; in fact, the HeGDC is required after about 1.5 × 10 21 more filled particles.…”

Section: Gas Adsorption Capacity and Lithium Saturationmentioning

confidence: 99%

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RFX-mod wall conditioning by lithium pellet injection

et al. 2012

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Plasma–wall interaction is one of the most important issues that present magnetic confinement devices have to face. In the RFX-mod reversed field pinch experiment plasma–wall interaction has become a hard point increasing plasma current up to the RFX-mod maximum design value of 2 MA, since in this case local power deposition can be as high as 10 MW m−2. Since the first wall of RFX-mod is entirely covered by graphite tiles different techniques have been tested to control hydrogen wall influx: He glow discharges cleaning, He discharges at high plasma currents, wall boronization and baking. With the best results obtained by boronization, at high plasma currents all such techniques improve the situation but do not allow a complete and stationary hydrogen influx reduction. Furthermore, in the presence of localized high power load the wall still responds providing very high influxes. In order to improve this situation wall conditioning by lithium has been tested. As a first lithization method to deposit a controllable amount of lithium on the wall, a room temperature pellet injector has been used (maximum pellet diameter of 1.8 mm and maximum length of 5 mm). Lithium coatings with a theoretical thickness of about 10 nm have been applied both to clean graphite tiles and over boronized ones. Lithization demonstrated to be effective in lowering hydrogen wall recycling to a value smaller than that of boronized graphite, with the effect lasting 20–30% more than in the boronized case. Compared with boronization, lithization slightly improves (by about 30%) particle confinement time and also clearly affects edge particle transport providing a lower edge density and more peaked density profiles. Lithization also reduces carbon content by about 10% over boronization but still no clear improvement has been observed in terms of energy confinement. Similar results have been obtained performing lithization over boronized graphite.

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Section: Lithium Pellet Injection Techniquementioning

confidence: 99%

Section: Gas Adsorption Capacity and Lithium Saturationmentioning

confidence: 99%

RFX-mod wall conditioning by lithium pellet injection

et al. 2012

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“…4 Other diagnostic concepts are being developed on RFX, such as measuring the pitch of the magnetic field lines by observing the cigar-shaped ablation cloud produced by a noncryogenic impurity pellet crossing the plasma. 5 Currently the most valuable internal magnetic diagnostic on RFX is, however, the five-chord far infrared ͑FIR͒ polarimeter, which is now under upgrading with the implementation of the sixth chord. 6 The system has recently given the first real insight of the internal magnetic structure in an RFP.…”

Section: Introductionmentioning

confidence: 99%

Integration of magnetic and nonmagnetic measurements for current profile reconstruction in RFX

Bagatin¹,

Chitarin²,

Desideri³

et al. 2001

Review of Scientific Instruments

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A crucial issue in magnetically conﬁned plasmas characterized by relevant internal current \ud redistribution, such as high beta and low ﬁeld toroidal devices, is the determination of their internal \ud magnetic structure. The article presents a method for the integration of magnetic and nonmagnetic \ud measurements in a model which considers a plasma described by stationary ideal \ud magnetohydrodynamic equilibrium equations, with toroidal and poloidal plasma currents \ud represented by distributed discrete ﬁlaments and current sheets. The model also includes the massive \ud conductors representing the vessel, the shell, and the machine windings. The discrete current sets are \ud determined by using as input data the total currents ﬂowing in the plasma, in the windings and in \ud the vessel, as deduced by external integral magnetic measurements. The obtained ﬁlamentary \ud current sets are then adjusted by imposing further constraints. One of the constraints is given by the \ud set of local magnetic ﬁeld measurements provided by external pickup coils. A further and more \ud signiﬁcant constraint is imposed by far infrared polarimeter, which gives an integral condition for \ud each implemented measurement chord. The method is validated by using experimental data from the \ud reversed ﬁeld pinch Reversed Field eXperiment, and the results suggest that the current density \ud distribution is rather different from that usually predicted by conventional data inversion algorithms

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“…In the mechanical separation technique, a sabot which holds a projectile or its equivalent in the launch tube is forced to separate, either in the caliber or out of the muzzle, by impinging against a solid stopper allowing only the projectile to pass intact. [2][3][4][5] The higher the muzzle speed, the more serious the damage done by the sabot and the stopper after impingement; the fragments and outgassing from the impact contaminate the test section, thereby leading to "dirty" experimental environments.…”

Section: Introductionmentioning

confidence: 99%

Impactless, in-tube sabot separation technique useful for modest-sized supersonic ballistic ranges

Sasoh

Oshiba

2006

Review of Scientific Instruments

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A simple and high performance sabot separation technique which is useful even in about 10-m-long supersonic ballistic ranges has been developed. The normal in-flight sabot separation distance is vastly reduced by adding an addition tube with no diaphragm that may cause damage to the projectile. The launch tube of the ballistic range is subdivided to the acceleration, ventilation, and sabot separation sections. In the ventilation section, both the precursor shock wave driven by the sabot when coasting through the acceleration section and the driver gas is vented out to the dump chamber. In the sabot separation section, only the sabot experiences a great dragging pressure imbalance whereas the drag to the projectile is kept negligible. Initially, the whole system except for the driver gas chamber is connected without any diaphragm; the range operation is not accompanied by any high-speed impact among the sabot, diaphragm, and other related solid parts. The experimental environment can be kept clean. The influence of the muzzle blast is eliminated within a reasonably short distance from the muzzle because it delays owing to the ventilation section. Calibration experiments and the demonstration of flow visualization and boom measurement of supersonic flight were conducted using a 25 mm bore, Mach-2 ballistic range.

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Noncryogenic pellet injector for diagnostic purposes on the RFX reversed field pinch

Cited by 7 publications

References 7 publications

RFX-mod wall conditioning by lithium pellet injection

RFX-mod wall conditioning by lithium pellet injection

Integration of magnetic and nonmagnetic measurements for current profile reconstruction in RFX

Impactless, in-tube sabot separation technique useful for modest-sized supersonic ballistic ranges

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