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This paper presents the experimental results of the (Bi,Pb)2Sr2Ca2Cu3O10 (BSCCO) coils impregnated with low-melting point metal, whose melting point is 60 °C. The coils were layer-wound without turn-to-turn insulation, i.e., no-insulation (NI). We fabricated the coils with polycarbonate bobbin and casing and the coils with aluminum alloy bobbins and casing. The coils with polycarbonate bobbin and casings showed severe degradation after impregnation. The coils with aluminum alloy ones showed less degradation. A long decay time of the magnetic field during a sudden discharge was measured. The decay time was shortened to be 1/39 by an inter-layer insulation with polyimide sheet. Partial insulation, i.e., electrical insulation between adjacent layers, was effective in reducing this long time constant, even for a BSCCO NI coil.

AbstractSpontaneous dynamics of magnetic islands depending on various plasma parameters in the Large Helical Device (LHD) are described. The structure of the magnetic island undergoes deformation during a discharge. There are two states of magnetic island; they are the growth and self-healing of the magnetic island. The self-healing occurs in the higher-beta and lower-collisionality plasmas. The magnetic island, on the other hand, grows in the lower-beta and higher-collisionality region. The self-healing phenomenon is realized by the disappearance of the local flattening of the Teprofile and the perturbed magnetic field structure compensating the externally imposed perturbation field to produce a seed magnetic island.

AbstractThis paper reviews progress in the study of pressure-driven interchange stability in the Large Helical Device (LHD) for 10 years. When the plasma approaches the boundary of ideal interchange mode, a strong magnetohydrodynamic (MHD) mode appears, leading to a distortion of pressure profile, although no major disruption is caused. The experiments for investigating magnetic shear effects in the magnetic hill configuration indicate that the reduction of magnetic shear leads to a minor collapse due to an excitation of low-order MHD mode. In the high-beta regime of more than 4%, MHD modes excited in the periphery with magnetic hill are observed to dominate, and it was found that the amplitude depends on the magnetic Reynolds number as well as the pressure gradient, which is qualitatively consistent with the prediction of resistive interchange mode. Also, experiments and theory for finding parameter dependence of the onset of the mode indicate that the onset is related to both the magnetic Reynolds number and the stability index of resistive interchange mode.

AbstractIn the vacuum of the Large Helical Device (LHD), we can change the plasma volume, the aspect ratio, the ellipticity, the rotational transform, and the height of the magnetic hill through the control of the vertical and the qudrupole components of the magnetic field and the helical coil pitch parameter. The two effects of the finite beta on the magnetohydrodynamic (MHD) configuration, the magnetic surface torus outward shift and the invasion of the stochastic region into the plasma core, are discussed. The former is qualitatively the same as that by the external vertical field control. According to the comparison between a theoretical prediction in the finite beta and the vacuum field calculation in the vertical field control, the latter effect is strongly affected by the nonaxisymmetric component of the equilibrium current. A theoretical prediction suggests that an MHD equilibrium beta limit different from the conventional one exists due to the lack of the equilibrium force balance in the stochastic region. The key parameters to improve the accuracy of the identification of the MHD equilibrium configuration are shown to be the identification of the toroidal current profile, the anisotropic pressure effect, and the identification of the plasma boundary shape.

AbstractThe magnetic configuration of the Large Helical Device (LHD) changes with the increment in beta. To distinguish between the beta effect and the configuration effect on the gradual degradation of the global confinement property in the high-beta LHD plasmas, the local transport characteristics are studied by considering the change in the major radius of the magnetic flux surface with the beta value. A model transport coefficient that has the same nondimensional parameter dependence as the international stellarator scaling 2004 (ISS04) is introduced and used as the reference. The dependence of the local transport characteristics in high-beta plasmas on the major radial position of a geometric center of the magnetic flux surface is compared with that in low-beta plasmas. The dependence of the local transport in the peripheral region is correlated more with beta itself than the magnetic configuration effect, whereas the core transport appears to be correlated more with the configuration effect. The comparison of the experimental transport coefficients and the calculation results shows that the resistive pressure gradient-driven turbulence can be considered as one of the causes of this degradation.

AbstractProgress in the integrated development of the helical system in the Large Helical Device (LHD) is described in this paper. Understanding of net current–free plasmas has been deepened in the extended operational regime. Geometrical optimization based on neoclassical theory has revealed that good confinement, equivalent to the tokamak H-mode, can be obtained in the collisionless regime. This approach has also demonstrated that anomalous transport is reduced simultaneously, which poses a working hypothesis that optimization of neoclassical transport suppresses turbulent anomalous transport as well. With regard to the magnetohydrodynamic instability, LHD has discovered that interchange instability is benign in the magnetic hill. These two findings have produced a synergistic effect on the enhancement of confinement and plasma β. Remarkable proof of the advantage of helical systems can be seen in very high density operation, which is not accessible in tokamaks. Abundant integrated knowledge about three-dimensional physics has been extracted from these achievements. This progress is important in the assessment of the potential of a helical fusion reactor and makes a significant complementary contribution to tokamaks as well.

In local island (m/n= 1/1) divertor discharges in the large helical device a stable super dense core plasma develops when a series of pellets are injected. A core region with a density as high as 4.6 × 1020?m?3and a temperature of 0.85?keV is maintained by an internal diffusion barrier with a very high density gradient. In a study of island dynamics, we find that an externally imposed large island (m/n= 1/1) as large as 15% of the minor radius is healed when beta at the island exceeds a critical value.

We study the effect of the net toroidal plasma current on the diamagnetic measurement for large toroidal current experiments in the Large Helical Device (LHD). In order to treat precisely the effect, we apply a new method that evaluates magnetic fluxes of magnetic measurements directly from plasma currents of a magnetohydrodynamic equilibrium state with net toroidal current. There is a large difference between the value calibrated by the new method and by a conventional method under the cylindrical and large aspect ratio plasma model. We calibrate the diamagnetic beta value using the net toroidal current distribution observed by motional Stark effect spectroscopy in a LHD discharge with a high net toroidal current, 40?kA?T?1. We obtain the results that the temporal behaviour of the calibrated diamagnetic beta value is quite the same with the beta value based on the profile measurement by Thomson scattering and far-infrared interferometry.

AbstractThe three-dimensional (3-D) VMEC code has been modified to model an energetic species with a variant of a Bi-Maxwellian distribution function that satisfies the constraint B·∇ℱh= 0, and the 3-D TERPSICHORE stability code has been extended to investigate the effects of pressure anisotropy in two limits. The lower limit is based on a purely fluid Kruskal-Oberman (KO) energy principle (ignoring the stabilizing kinetic integral), and the upper limit is obtained from an energy principle in which the hot particle pressure and current density refrain from interacting with the dynamics of the instability because their diamagnetic drift frequency is considered much larger than the dominant growth rate. We have specifically investigated the instability properties of a Heliotron device with a major radius of 3.9 m and total 〈β〉 ≃ 3.9%, where the energetic particle contribution 〈βh〉 varies from 0 to 1.3% for T‖/T┴= 4. Both models demonstrate a significant stabilization of a global m/n = 4/2 mode as 〈βh〉/〈β〉 approaches 1/3, with the noninteracting (NI) hot particle model virtually reaching the point of marginal stability when 〈βh〉/〈β〉 ≃ 1/4. A variation of T‖/T┴at fixed 〈βh〉/〈β〉 = 1/3 shows a noticeable decrease in the absolute magnitude of the unstable eigen-value in the range 1 ≤ T‖/T┴≤ 2 in the fluid KO model. The NI energetic particle model remains near marginality in the range 1 ≤ T‖/T┴≤ 4. The Mercier stability is consistent with the global mode calculations. Performance benchmarks of the TERPSICHORE code on several different computers are presented

AbstractThis paper describes recent progress in magnetohydrodynamics (MHD) study of high-beta plasmas of the Large Helical Device. Control of the plasma aspect ratio (Ap) in the range of 6.3 to 8.3 was done in order to optimize the configuration for high-beta plasma production and to investigate the MHD characteristics. The experiments brought a maximum average beta of 4.3% at the Ap= 6.6 configuration. MHD activities in the periphery are dominantly observed in such a high-beta region, and their amplitudes increase with decreasing magnetic Reynolds number (S) and have clear dependence on the Sparameter. When the plasma aspect ratio is increased, minor collapse due to the m/n= 1/1 mode without rotation occurs. It is enhanced further by the plasma current reducing magnetic shear and degrades the beta value by >50%. The results are expected to give important information on the operation regime and the future design of the helical fusion reactor and to contribute to experimental knowledge of ideal and resistive instability.

AbstractRemarkable progress to access the reactor-relevant regime has been made in a recent experiment in the Large Helical Device. Optimizing the rotational transform, the average beta value of 4.3%, which is the highest record among helical devices, was achieved. The high-performance plasma with a fusion triple product up to ~2.2 × 1019m−3·keV·s was sustained for >7 s by repetitive hydrogen pellet injection. With regard to steady-state operation, which is one of the key issues to realize a fusion reactor, discharges for >30 min were successfully sustained by ion cyclotron range of frequency heating with the aid of the magnetic axis swing technique to reduce the heat load to the plasma-facing component. In the discharge, the total input energy to the plasma reached 1.3 GJ, which also established a new record.

A formulation of the anisotropic pressure magnetohydrodynamic equilibrium problem for three-dimensional plasmas with imposed nested magnetic surfaces is developed based on a bi-Maxwellian model of the distribution function for the energetic particle species. The hot particle distribution function satisfies the constraint . Large parallel and perpendicular anisotropy factors can be explored within the model through the choice of the hot particle perpendicular to parallel temperature ratio T/T||. A fixed boundary version of the VMEC code has been adapted to numerically compute three-dimensional anisotropic pressure equilibria. Applications to a 10-field period Heliotron device and a 2-field quasiaxisymmetric stellarator demonstrate that the pressures do not vary significantly around the magnetic surfaces when the total parallel pressure p||is larger than its perpendicular counterpart p. For off-axis hot particle deposition with p> p||, pconcentrates in the region where the energetic particles are generated. On the other hand, p||is distributed roughly uniformly around the flux surfaces in the Heliotron but is localized on the low field side in the quasiaxisymmetric machine. The hot particle density structure correlates more closely with the corresponding perpendicular rather than with parallel pressure. The specific form for the definition of ? that best correlates with the Shafranov shift is identified.

In the Large Helical Device, the structure of localized oscillations at the m/n= 2/1 rational surface during neutral beam (NB) injection in the counter direction (counter-NB injection) has been investigated in detail using an electron cyclotron emission (ECE) diagnostic. Here mand nare poloidal and toroidal mode numbers, respectively. Under the condition of increasing plasma current in the counter direction and nearly constant pressure, the oscillations are observed at larger magnitudes of plasma current (?20?kA?T?1). In the NB reversal experiments, where the direction of the NB is changed from the co- to the counter-direction and vice versa, the oscillations were observed only for the former case. These results suggest that the profile and magnitude of the plasma current play an important role in the mode onset. Analysis based on the Mercier criteria shows that for a flat or a hollow current profile an interchange mode becomes more unstable at higher negative plasma current, showing a tendency similar to the experimental observations. In addition, radial displacement due to the localized oscillations evaluated from electron temperature perturbation profiles with the ECE diagnostic agrees well with that predicted by a three-dimensional ideal magnetohydrodynamic stability code.

In low density discharges of a Large Helical Device (LHD), anisotropic pressure is expected because the LHD has powerful tangential neutral beam injection systems. We study the behaviour of the ratio of the observed saddle loop flux to the diamagnetic flux, and the results are compared with the predicted beam pressure anisotropy by a Monte Carlo technique and the steady state Fokker–Planck solution. We show the possibility of the degree of pressure anisotropy being estimated by magnetic measurements in the LHD.

In the Large Helical Device (LHD), the highest operational averaged beta value has been expanded from 3.2% to 4% in the last 2 years by increasing the heating capability and exploring a new magnetic configuration with a high aspect ratio. Although the magneto-hydrodynamic (MHD) stability properties are considered to be unfavourable in the new high aspect configuration, the heating efficiency due to neutral beams and the transport properties are expected to be favourable in a high-beta range. In order to clarify the effect of the global ideal MHD unstable mode on the operational regimes in helical systems, especially the beta gradients in the peripheral region and the beta value, the MHD analysis and the transport analysis are performed in a high-beta range of up to 4% in LHD. In a high-beta range of more than 3%, the maxima of the observed thermal pressure gradients at a low order rational magnetic surface in the peripheral region are marginally unstable to the low-mode-number ideal MHD instability. Though a gradual degradation of the local transport in the region has been observed as beta increases, a disruptive degradation of the local transport does not appear in the beta range up to 4%.

The Large Helical Device is a heliotron device with L = 2 and M = 10 continuous helical coils with a major radius of 3.5–4.1 m, a minor radius of 0.6 m and a toroidal field of 0.5–3 T, which is a candidate among toroidal magnetic confinement systems for a steady state thermonuclear fusion reactor. There has been significant progress in extending the plasma operational regime in various plasma parameters by neutral beam injection with a power of 13 MW and electron cyclotron heating (ECH) with a power of 2 MW. The electron and ion temperatures have reached up to 10 keV in the collisionless regime, and the maximum electron density, the volume averaged beta value and stored energy are 2.4 × 1020 m−3, 4.1% and 1.3 MJ, respectively. In the last two years, intensive studies of the magnetohydrodynamics stability providing access to the high beta regime and of healing of the magnetic island in comparison with the neoclassical tearing mode in tokamaks have been conducted. Local island divertor experiments have also been performed to control the edge plasma aimed at confinement improvement. As for transport study, transient transport analysis was executed for a plasma with an internal transport barrier and a magnetic island. The high ion temperature plasma was obtained by adding impurities to the plasma to keep the power deposition to the ions reasonably high even at a very low density. By injecting 72 kW of ECH power, the plasma was sustained for 756 s without serious problems of impurities or recycling.

A rapid bifurcation of the equilibria with and without a large island (n/m= 1/1) has been observed in the medium to high beta large helical device discharges. A large island imposed by an external resonant field is suddenly suppressed nearly perfectly by the plasma effects when the beta at the ?/2? = 1 surface exceeds a critical value. The critical beta value is nearly proportional to the externally imposed resonant field normalized by the main field strength.

One of the main objectives of LHD is to extend the plasma confinement database for helical systems and to demonstrate such extended plasma confinement properties to be sustained in the steady state. Among the various plasma parameter regimes, the study of confinement properties in the collisionless regime is of particular importance. Electron cyclotron resonance heating (ECRH) has been extensively used for these confinement studies of LHD plasma from the initial operation. The system optimizations including the modification of the transmission and antenna system are performed with special emphasis on the local heating properties. As a result, a central electron temperature of more than 10?keV with an electron density of 0.6 × 1019?m?3is achieved near the magnetic axis. The electron temperature profile is characterized by a steep gradient similar to those of an internal transport barrier observed in tokamaks and stellarators. The 168?GHz ECRH system demonstrated efficient heating at densities more than 1.0 × 1020?m?3. The continuous wave ECRH system is successfully operated to sustain a 756?s discharge.

Fixed boundary three-dimensional anisotropic pressure equilibria are computed that are consistent with a family of distribution functions that load particles preferentially towards v?vand model the effects of balanced tangential neutral beam injection. The total pressure surfaces remain coupled with the magnetic surfaces even when the parallel beam pressure greatly exceeds its perpendicular counterpart. The anisotropy factors and the Shafranov shift, which increases with the anisotropy, are calculated in a currentless two-field period quasiaxisymmetric stellarator device.

AbstractRecent progress in the Large Helical Device (LHD) experiment during the last 2 yr is reviewed. The LHD has been extending its operational regime toward fusion-relevant conditions while taking advantage of the net-current-free heliotron concept employing a superconducting coil system. Heating capability has exceeded 10 MW, and the central ion and electron temperatures have reached 7 and 10 keV, respectively. The maximum values of beta and pulse length have been extended to 3.2% and 150 s, respectively. Several encouraging physics observations have been obtained, i.e., simultaneous achievement of the mitigation of the magnetohydrodynamic instability criteria and good confinement, and formation of an internal transport barrier. The initial results have been obtained using a local island divertor, which shows the possibility of particle control at the plasma edge.

Characteristics of MHD instabilities and their impacts on plasma confinement are studied in current free plasmas of the Large Helical Device. Spontaneous L–H transition is often observed in high beta plasmas close to 2% at low toroidal fields (B_t  0.75 T). The stored energy starts to rise rapidly just after the transition accompanying the clear rise in the electron density but quickly saturates due to the growth of the m = 2/n = 3 mode (m and n: poloidal and toroidal mode numbers), the rational surface of which is located in the edge barrier region, and edge localized mode (ELM) like activities having fairly small amplitude but high repetition frequency. Even in low beta plasmas without L–H transitions, ELM-like activities are sometimes induced in high performance plasmas with a steep edge pressure gradient and transiently reduce the stored energy up to 10%. Energetic ion driven MHD modes such as Alfvén eigenmodes (AEs) are studied in a very wide range of characteristic parameters (the averaged beta of energetic ions, 〈β_b∥〉, and the ratio of energetic ion velocity to the Alfvén velocity, V_b∥/V_A), of which range includes all tokamak data. In addition to the observation of toroidicity induced AEs (TAEs), coherent magnetic fluctuations of helicity induced AEs (HAEs) have been detected for the first time in NBI heated plasmas. The transition of a core-localized TAE to a global AE (GAE) is also observed in a discharge with temporal evolution of the rotational transform profile, having a similarity to the phenomenon observed in a reversed shear tokamak. At low magnetic fields, bursting TAEs transiently induce a significant loss of energetic ions, up to 40% of injected beams, but on the other hand play an important role in triggering the formation of transport barriers in the core and edge regions.

This paper reports results on the progress in steady-state high-β_p ELMy H-mode discharges in JT-60U. A fusion triple product, n_D(0)τ_ET_i(0), of 3.1 × 10²⁰ m⁻³ s keV under full non-inductive current drive has been achieved at I_p = 1.8 MA, which extends the record value of the fusion triple product under full non-inductive current drive by 50%. A high-beta plasma with β_N ~ 2.7 has been sustained for 7.4 s (~60τ_E), with the duration determined only by the facility limits, such as the capability of the poloidal field coils and the upper limit on the duration of injection of neutral beams. Destabilization of neoclassical tearing modes (NTMs) has been avoided with good reproducibility by tailoring the current and pressure profiles. On the other hand, a real-time NTM stabilization system has been developed where detection of the centre of the magnetic island and optimization of the injection angle of the electron cyclotron wave are done in real time. By applying this system, a 3/2 NTM has been completely stabilized in a high-beta region (β_p ~ 1.2, β_N ~ 1.5), and the beta value and confinement enhancement factor have been improved by the stabilization.

Energy confinement and heat transport of net-current-free NBI heated plasmas in the large helical device (LHD) are discussed with emphasis on density and power deposition profile dependences. Although the apparent density dependence of the energy confinement time has been demonstrated in a wide parameter range in LHD, the loss of this dependence has been observed in the high density regime under specific conditions. Broad heat deposition due to off-axis alignment and shallow penetration of neutral beams degrades the global energy confinement while the local heat transport maintains a clear temperature dependence, lying between Bohm and gyro-Bohm characteristics. The central heat deposition tends towards an intrinsic density dependence like τE∝(n¯e/P)0.6 from the state where density dependence is lost. The broadening of the temperature profile due to the broad heat deposition profile contrasts with the invariant property that has been observed widely as profile resilience or stiffness in tokamak experiments. The confinement improvement as a result of the inward shift of the magnetic axis is obvious in the core region, which emphasizes the improvement of transport because of the geometry being unfavourable for the central heating of NBI in this configuration. The edge pressure, clearly, does not depend on the magnetic axis position. Unlike a tokamak H-mode, the edge pressure is determined by transport and can be increased by increasing the heating power.

Significant progress has been made with ion cyclotron range of frequencies (ICRF) heating in the Large Helical Device. This is mainly due to better confinement of the helically trapped particles and less accumulation of impurities in the region of the plasma core. During the past two years, ICRF heating power has been increased from 1.35 to 2.7 MW. Various wave-mode tests were carried out using minority-ion heating, second-harmonic heating, slow-wave heating and high-density fast-wave heating at the fundamental cyclotron frequency. This fundamental heating mode extended the plasma density range of effective ICRF heating to a value of 1×1020 m−3. This use of the heating mode was its first successful application in large fusion devices. Using the minority-ion mode gave the best performance, and the stored energy reached 240 kJ using ICRF alone. This was obtained for the inward-shifted magnetic axis configuration. The improvement associated with the axis-shift was common for both bulk plasma and highly accelerated particles. For the minority-ion mode, high-energy ions up to 500 keV were observed by concentrating the heating power near the plasma axis. The confinement properties of high-energy particles were studied for different magnetic axis configurations, using the power-modulation technique. It confirmed that with the inward-shifted configuration the confinement of high-energy particles was better than with the normal configuration. By increasing the distance of the plasma to the vessel wall to about 2 cm, the impurity influx was sufficiently reduced to allow sustainment of the plasma with ICRF heating alone for more than 2 min.

The most important finding in the Large Helical Device (LHD) experiments so far is that an inward-shifted configuration exhibits good plasma performance with a scaling similar to that of ELMy H-mode tokamaks. The inward-shifted configuration has been predicted to have unfavourable magnetohydrodynamic (MHD) properties, even though it has significantly better particle-orbit properties. However, no serious confinement degradation due to the MHD activities was observed, resolving favourably the potential conflict between stability and confinement. Neoclassical transport loss can be suppressed even in a low-collisionality regime, and in this way the inward-shifted configuration was shown to make the LHD plasma properties favourable. Then, it is very important to realize more improved plasma performance and higher temperature plasmas for extending the plasma-parameter regime in order to obtain data that can be extrapolated to a reactor. In the fifth campaign in 2001–2002, an increase in the heating power achieved an electron temperature T_e of over 10 keV and an ion temperature T_i of 5 keV. A T_e profile, which is characteristic of internal transport barriers, was also observed when the electron cyclotron resonance heating power was highly focused on the centre of the plasma sustained by neutral beam injection.

In current-free stellarators, the parallel current density is normally too weak to drive global external kink modes. However, at finite values of β, the bootstrap current (BC) can provide sufficient free energy to trigger this class of mode in some stellarator systems. The effect of the BC in the collisionless 1/ν regime has been investigated in several different types of stellarator reactor systems all with a volume V~1000 m³. In quasiaxisymmetric and quasihelically symmetric stellarators, the BC is large at finite β and this can cause low order resonances to move into and emerge out of the plasma which in turn can destabilize global internal and external kink modes. In a six-field period system with poloidally closed contours of the magnetic field strength B, the BC is small and decreases the rotational transform only slightly. As a result, only intermediate to high n modes can become weakly destabilized. Furthermore, it is demonstrated in this system that the contours of the second adiabatic invariant &calJ;_‖ close poloidally for all trapped particles at finite β*~6&percent;. This condition leads to the loss of a very small fraction of the collisionless α-particle orbits. In Sphellamak configurations with peaked toroidal currents required to generate nearly isodynamic maximum-B confining field structures, the BC accounts only for a small fraction of the total current. The loss of α-particles born within the inner quarter of the plasma volume is negligible while about (1/3) of those born at half volume escape the device within a slowing down time.

Effects of MHD activities on the pressure profile in NBI plasmas in the range of ⟨β⟩≤3% have been investigated in Large Helical Device (LHD). The ⟨β⟩ dependence of the n/m = 1/2 mode in the core region and the ι = 1 resonant modes in the peripheral region are focused. The n/m = 1/2 mode has been observed in the ⟨β_dia⟩ range of less than 2.3% and disappears when the plasma reaches the Mercier stable region. The pressure profile becomes broader with increasing ⟨β⟩, and a large pressure gradient forms in the peripheral region. The amplitudes of the ι = 1 resonant modes in the peripheral region increase monotonically with ⟨β⟩.

Recent experimental results in the Large Helical Device have indicated that a large pressure gradient can be formed beyond the stability criterion for the Mercier (high-n) mode. While the stability against an interchange mode is violated in the inward-shifted configuration due to an enhancement of the magnetic hill, the neoclassical transport and confinement of high-energy particle are, in contrast, improved by this inward shift. Mitigation of the unfavourable effects of MHD instability has led to a significant extension of the operational regime. Achievements of the stored energy of 1 MJ and the volume-averaged beta of 3% are representative results from this finding. A confinement enhancement factor above the international stellarator scaling ISS95 is also maintained around 1.5 towards a volume-averaged beta, ⟨β⟩, of 3%. Configuration studies on confinement and MHD characteristics emphasize the superiority of the inward-shifted geometry to other geometries. The emergence of coherent modes appears to be consistent with the linear ideal MHD theory; however, the inward-shifted configuration has reduced heat transport in spite of a larger amplitude of magnetic fluctuation than the outward-shifted configuration. While neoclassical helical ripple transport becomes visible for the outward-shifted configuration in the collisionless regime, the inward-shifted configuration does not show any degradation of confinement deep in the collisionless regime (ν*<0.1). The distinguished characteristics observed in the inward-shifted configuration help in creating a new perspective of MHD stability and related transport in net current-free plasmas. The first result of the pellet launching at different locations is also reported.