A multi-purpose reciprocating probe drive system for studying the effect of gas-puffs on edge plasma dynamics in the ADITYA-U tokamak

Abha Kanik; Abhijeet Kumar; Ankit Kumar; Ankit Patel; Ashok K. Kumawat; Bharat Hegde; D.C. Raval; Devilal Kumawat; Harshita Raj; Injamul Hoque

REVIEW 3 major objections 5 minor 41 references

A multi-purpose reciprocating probe drive system for studying the effect of gas-puffs on edge plasma dynamics in the ADITYA-U tokamak

T0 review · 3 major / 5 minor · reviewed 2026-08-10 · deepseek-v4-flash

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Pith's one-line read A servo-driven reciprocating probe maps gas-puff effects as deep as 3–4 cm inside the ADITYA-U tokamak edge.

desk verdict Solid diagnostic engineering paper whose headline physics number needs a position-calibration caveat. read the letter →

arxiv 2501.04462 v1 pith:5MOSBO72 submitted 2025-01-08 physics.plasm-ph

Kaushlender Singh , Bharat Hegde , Ashok K. Kumawat , Ankit Kumar , M.S. Khan , Suman Dolui , Injamul Hoque , Tanmay Macwan

show 19 more authors

Sharvil Patel Abha Kanik Komal Yadav Soumitra Banerjee Harshita Raj Devilal Kumawat Pramila Gautam Rohit Kumar Suman Aich Laxmikanta Pradhan Ankit Patel Kalpesh Galodiya Abhijeet Kumar Shwetang Pandya K. M. Patel K. A. Jadeja D.C. Raval R. Tanna Joydeep Ghosh

This is my paper · ORCID

classification physics.plasm-ph PACS 52.55.Fa52.70.-m

keywords reciprocatingprobedriveLangmuirtokamakedgeplasmagaspuffADITYA-Umagneticfluctuationsdiagnostics

verification ladder T0 review T1 audit T2 compute T3 formal

The pith

A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.

The reading

This paper reports the design, construction, and operation of a high-speed reciprocating drive system (HRDS) for the ADITYA-U tokamak, with interchangeable probe heads that can be moved radially through the edge plasma during a discharge. The central result is that a fuel gas-puff alters plasma density, temperature, potential, and their fluctuations as deep as roughly 3–4 cm inside the last closed magnetic flux surface (LCFS), flattening the radial profiles of these quantities in the far-edge region. This matters because fixed probes on ADITYA-U can survive only about 1 cm inside the limiter radius, so the radial reach of gas-puff influence had not been directly measured before. The paper shows the drive is fully operational, does not noticeably perturb the discharge, and can carry both Langmuir and magnetic probe arrays.

What carries the argument

The load-bearing object is the HRDS itself: a brushless synchronous servo motor mounted about 2.5 m from the vessel, driving a spindle with a 20 mm pitch that compresses a 1.4 m edge-welded bellow, so the probe shaft moves radially while the motor stays in a ~30 G field region. Two laser-photodiode pairs measure the average plate speed ($v_{\mathrm{avg}}=\Delta x/\Delta t$), and a one-to-one correspondence between the plate and the probe shaft converts each probe tip's time trace into a radial profile with 8 mm spacing between tips. The interchangeable heads are an 8-tip molybdenum Langmuir rake for $n_e$, $T_e$, $V_p$, and fluctuations, and five MACOR-encased magnetic coils for poloidal field fluctuations; both are rated to survive the ~5 MW/m² heat load of a fast transit. The machinery's job is to let a single discharge serve as a radial scan without the probe damage that fixed probes suffer beyond ~1 cm inside the limiter.

What would settle it

Measure probe-tip position in situ during a tokamak discharge, for example by encoding shaft position or by comparing a reciprocating profile against fixed probes at several matched radii; if the reciprocating density or temperature profile disagrees with fixed probes by more than the 8 mm probe spacing, the time-to-radius mapping is wrong. A repeat-stroke test in which the probe returns at different speeds should yield identical radial profiles if the mapping is speed-independent.

Watch

Extended reading notes

Core claim

On the paper's own terms, the discovery is that a servo-motor-driven reciprocating probe with a long bellows can place an 8-tip Langmuir probe array and a 5-coil magnetic probe array inside the LCFS during the flat-top phase of an ADITYA-U discharge, and that measurements made this way reveal gas-puff effects much deeper than previously accessible. In discharges with and without periodic hydrogen gas-puffs, the HRDS shows that the puff reduces the mean density, temperature, and floating potential inside the LCFS and flattens their radial profiles, while also reducing the fluctuations that drive edge transport. The magnetic probe head records poloidal magnetic field fluctuations inside the LCFS that match fixed Mirnov-coil signals, and it observes reduced magnetic fluctuation with gas injection. These observations support the claim that the gas puff influences edge plasma dynamics up to 3–4 cm inside the LCFS.

Load-bearing premise

The radial position of each probe tip during a discharge is inferred from laser-photodiode speed measurements taken in the lab and a one-to-one correspondence between the drive plate and shaft, checked only in GDC plasma; if that mapping drifts during real tokamak discharges, the radial profiles and the 3–4 cm claim would be off by an unknown amount.

Editorial extensions

If this is right

Gas-puff flattening of $n_e$, $T_e$, and $V_p$ profiles several centimetres inside the LCFS implies that gradient-driven turbulence in this region is directly modified by fuelling, not just by processes in the scrape-off layer.
Because the probe movement changes plasma current, SXR emission, edge density, and edge potential by less than 2%, each discharge can be used as a clean radial scan without perturbing the plasma being measured.
The magnetic probe head records poloidal magnetic fluctuations inside the LCFS that match fixed Mirnov-coil measurements, extending gas-puff studies of magnetic fluctuations to previously inaccessible radii.
The interchangeable-head design makes the same drive reusable for Mach probes, ball-pen probes, retarding field energy analysers, electrode biasing, and even fuel injection inside the LCFS.
Operation up to radial location $\rho \sim 0.8$ gives ADITYA-U a new diagnostic reach in the far-edge region for future gas-puff and transport experiments.

Reading between the lines

Editorial extensions of the paper, not claims the author makes directly.

Editorial inference: the same plate-to-shaft position mapping could be checked shot-to-shot by adding an encoder on the shaft; if it holds, the HRDS can produce a full radial profile in a single discharge, saving machine time on profile campaigns.
Editorial inference: because the gas-puff effect is measured down to 3–4 cm inside the LCFS, models of fuelling and transport in ADITYA-U-sized devices should include edge-region sources at least that deep, rather than treating gas-puff effects as a scrape-off-layer boundary phenomenon.
Editorial inference: a servo-driven reciprocating probe of this type could be adapted to other small and medium tokamaks where port space is tight and the motor must be kept far from the machine; the ~30 G operating threshold gives a concrete design constraint.

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Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, and a circularity audit.

Desk Editor's Note

read the letter

This paper is worth a look if you care about edge diagnostics: it describes a servo-driven reciprocating probe for ADITYA-U, with interchangeable Langmuir and magnetic probe heads, and reports that fuel gas-puffs affect edge density, temperature, potential, and fluctuations up to 3-4 cm inside the LCFS. The engineering is the strong part. The torque calculations, leak testing, and speed measurements are careful, the GDC validation is a genuine cross-check, and the comparison of moving vs fixed probes in tokamak discharges is a sensible way to show the probe itself isn't perturbing the plasma. The interchangeable heads and the magnetic fluctuation data inside the LCFS are new for ADITYA-U.

The soft spot is the radial position mapping. The probe position is derived from an average speed measured between two photodiodes, during a motion that deliberately includes 12.5 m/s^2 acceleration. That introduces a position error on the order of a centimeter when the probe is still accelerating or decelerating. The GDC calibration checks repeatability against manual placement, but it isn't described as a full absolute calibration, and the tokamak comparison at r=26 cm also uses the same velocity assumption. So the precise number '3-4 cm inside the LCFS' carries an unquantified ~1 cm uncertainty. That doesn't kill the physics claim—the gas puff clearly affects the edge well inside the LCFS—but it means the specific depth should be presented with an error bar or a more conservative statement.

Also, the physics results come from single discharges, with no shot-to-shot statistics or error bars on the radial profiles. For a diagnostic paper that's acceptable at this stage, but it should be acknowledged more explicitly. The data are available on request, which is good practice, though no public dataset is linked.

Overall, this is a serious, honest piece of work. It deserves peer review. A referee should ask for a position calibration that accounts for the acceleration profile (or an uncertainty estimate), and for error bars on the reported depth. The core engineering contribution is solid, and the measurement is a genuine step beyond what fixed probes could do on ADITYA-U.

Referee Report

3 major / 5 minor

Summary. The paper reports the design, fabrication, installation, and operation of a high-speed reciprocating drive system (HRDS) for the ADITYA-U tokamak. The system uses a servo motor and edge-welded bellow to translate interchangeable Langmuir and magnetic probe heads across the edge plasma, with a claimed penetration of up to ~5 cm inside the last closed flux surface. Section 5 presents measurements from a rake Langmuir probe head and a magnetic probe head, and from these data the authors conclude that fuel gas-puffs affect mean and fluctuating plasma parameters (density, temperature, potential, and magnetic fluctuations) up to 3–4 cm inside the LCFS, flattening radial profiles and reducing fluctuations. The paper also documents the mechanical design, torque calculations, vacuum tests, and the GDC-plasma validation of the probe motion.

Significance. If the diagnostic performance and the physics claims hold, the HRDS would be a valuable new capability for ADITYA-U and a useful reference for similar reciprocating probe systems on small and medium tokamaks. The engineering design is presented in detail, with concrete numbers for torque, leak rate, and speed; the authors also demonstrate that the probe motion does not noticeably perturb the plasma in a comparison discharge. The physics result regarding the radial extent of gas-puff influence is qualitatively plausible and consistent with prior ADITYA-U observations, but its quantitative strength depends on accurate probe-position mapping and on the reproducibility of single-discharge measurements. The paper would benefit from a focused revision to substantiate this central claim with error analysis and multi-discharge statistics.

major comments (3)

[§3 and §5, Eq. (1) and Fig. 8] The radial position mapping is a load-bearing issue for the central claim that gas-puffs affect plasma parameters up to 3–4 cm inside the LCFS. In §3 the probe speed is measured as an average between two laser-photodiode pairs, v_avg = Δx/Δt, and in §5 positions are assigned by assuming constant velocity (e.g., 'with a probe velocity of ~0.5 m/s, it reaches r = 26 cm at ~80 ms'). However, the system is operated with an acceleration of 12.5 m/s², so the time–radius relation is not linear. Over the first 40 ms of travel from rest, the constant-speed assumption underestimates the distance by roughly 1 cm (v²/2a ≈ 1 cm). The GDC validation in Fig. 5b shows repeatability of the inferred locations but is not an independent absolute calibration under tokamak discharge conditions. Because the depth of gas-puff influence is quantified as '3–4 cm inside LCFS', a ~1 cm position uncertainty leaves this headline claim quantitatively insecure. Please provide an independent position measurement during tokamak operation (e.g., motor encoder trace or a second position sensor), quantify the position uncertainty, and recalculate the radial profiles and the inferred penetration depth.
[§5, Figs. 8(c)–8(e)] The radial profiles of plasma density, floating potential, and temperature before and after gas-puffs are each based on a single discharge (e.g., #36968 for V_f and n_e, #36971 for T_e) and are presented without error bars or any statistical significance estimate. The claim that gas-puffs 'flatten' the profiles and influence parameters up to 3–4 cm inside the LCFS requires comparing the before/after difference against the natural discharge-to-discharge variability and the internal fluctuation level. I recommend either repeating the measurement in multiple comparable discharges and showing shot-to-shot scatter, or at minimum providing a quantitative estimate of the uncertainty on each radial-bin mean (e.g., from time fluctuations within the bin) and a statistical test of the before/after difference.
[§5, Figs. 7 and 8] The methodology for converting the moving-probe time traces into radial profiles is not described in sufficient detail. The probe moves during the discharge, and gas-puff pulses are periodic; to obtain a radial profile 'before' and 'after' a puff, one must assign each time sample to a radial position and to a puff phase, and then combine data from the eight probe tips. The paper does not specify the time windows used for the before/after states, how the time-to-radius conversion is applied to the full trace (including acceleration phases), or how the individual probe-tip data are averaged. Without this information, the radial profiles in Fig. 8 are not reproducible. Please add a short paragraph or an explicit analysis section describing the exact procedure.

minor comments (5)

[Throughout] The abbreviation 'HDRS' appears in multiple places (e.g., §3, §4, §5, §6) but the system is introduced as 'HRDS'; please standardize to one abbreviation.
[§2] In the sentence listing design challenges, the required scan time and velocity are given in item 1 ('4-5 cm within 100-120 ms, requiring an average probe head velocity of 0.4-0.6 m/s') while in §3 the achieved velocity is stated as ~0.5 m/s and the acceleration as 12.5 m/s². The relationship between these numbers and the 'optimal operation conditions' would be clearer if the velocity, acceleration, and stroke-length values were reconciled explicitly with the torque calculations.
[§3, Figure 4] Figure 4 contains subfigures (a)–(f), but the text refers to 'Figure 4b' twice with different meanings (once for the laser/photodiode schematic and once for the LP design). Please renumber the subfigures and update the in-text callouts.
[§5, Figure 8] In Figure 8, the labels in panels (c), (d), and (e) are ambiguous: the text states '(c) for V_f; (d) for n_e' but the caption text says '(d) for V_f' in one place. Please ensure the figure and caption are consistent, and add axis labels and units for all panels.
[§1] The claim that pre-fixed probes can be placed only up to ~1 cm inside the limiter radius (r = 24 cm, ρ ~ 0.96) is stated without a supporting reference or data; since it motivates the need for the HRDS, please provide a citation or a brief experimental description.

Circularity Check

0 steps flagged · score 0.0 of 10

No circularity: the central claims are direct experimental measurements with external benchmarks, not derived from fitted parameters or self-referential definitions.

full rationale

This paper is an experimental diagnostic development and measurement report, not a derivation. The central claim that gas-puffs affect plasma parameters 3–4 cm inside the LCFS is obtained from direct Langmuir probe measurements of density, temperature, and floating potential before and after gas-puff injection (Section 5, Figures 8c–8e), with the reciprocating probe compared against fixed Langmuir probes at r = 26 cm (Figure 8a–8b) and magnetic probes compared against a fixed Mirnov coil (Figure 9). The probe position mapping is validated separately in GDC plasma by comparing reciprocating and manually placed probe measurements (Section 4, Figure 5b). No parameter is fitted to a subset of data and then renamed as a prediction; no equation in the paper reduces to its own input; no uniqueness theorem or ansatz is imported from prior authors. The paper does cite prior ADITYA-U work by the same group (e.g., Ref. [4] for gas-puff fluctuation suppression, Refs. [6–7] for cold-pulse and tearing-mode effects), but these citations are used as context and interpretation, not as the evidence for the new measurements presented here. Even if the cited interpretation were wrong, the measured flattening of radial profiles and the fixed-probe comparisons would remain independent experimental facts. The only notable weakness is the uncertainty in the probe velocity/position mapping under acceleration, which is a correctness/calibration concern, not a circularity concern: the position is measured by laser-photodiode timing and cross-checked, not derived from the plasma quantities it is used to interpret. Therefore no load-bearing circular step exists, and the appropriate score is 0.

Assumptions & free parameters 0 free parameters · 4 assumptions · 0 invented entities

The central claim rests on standard probe theory, an assumed position mapping, negligible probe perturbation, and a causal attribution to the gas puff. No free parameters are fitted to data. No new physical entities are introduced.

assumptions (4)

domain assumption Standard Langmuir probe theory (Mott-Smith and Langmuir) is valid for interpreting ion saturation current and floating potential as measures of density, temperature, and plasma potential in the moving probe head.
The paper converts ion saturation current and floating potential into ne, Te, and Vf without assessing effects of probe motion, sheath expansion, or Mach number on the interpretation. This enters in Section 5 where profiles are presented.
domain assumption The radial position of the probe tips during motion is accurately determined from the laser-photodiode speed measurement and the one-to-one correspondence between end-plate and shaft motion.
The position mapping is validated only in GDC plasma (Section 3, Fig. 5b) and is assumed to hold in tokamak discharges. This is the load-bearing premise for the radial profiles in Fig. 8.
domain assumption The moving probe head does not perturb the local plasma in a way that biased the measured parameters or the gas-puff comparison.
The paper shows less than 2% variation in global discharge parameters due to probe movement (Section 4, Fig. 6), but local perturbation at the probe head is not directly measured.
domain assumption The observed flattening of radial profiles after gas puff is caused by the gas puff and not by discharge variability or probe-induced effects.
The comparison is made between limited time windows in a small number of discharges, without statistical control or error analysis (Section 5, Fig. 8).

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Cite this review

Pith. "Pith review of A multi-purpose reciprocating probe drive system for studying the effect of gas-puffs on edge plasma dynamics in the ADITYA-U tokamak." pith.science (2026). https://pith.science/paper/5MOSBO72

@misc{pith2026250104462,
  author       = {Pith},
  title        = {Pith review of: A multi-purpose reciprocating probe drive system for studying the effect of gas-puffs on edge plasma dynamics in the ADITYA-U tokamak},
  year         = {2026},
  howpublished = {\url{https://pith.science/paper/5MOSBO72}},
  note         = {Machine review of arXiv:2501.04462}
}

read the original abstract

This article reports the development of a versatile high-speed reciprocating drive system (HRDS) with interchangeable probe heads to characterize the edge plasma region of ADITYA-U tokamak. This reciprocating probe drive system consisting of Langmuir and magnetic probe heads, is designed, fabricated, installed, and operated for studying the extent of fuel/impurity gas propagation and its influence on plasma dynamics in the far-edge region inside the last closed magnetic flux surface (LCFS). The HRDS is driven by a highly accurate, easy-to-control, dynamic, brushless, permanently excited synchronous servo motor operated by a PXI-commanded controller. The system is remotely operated and allows for precise control of the speed, acceleration, and distance traveled of the probe head on a shot-to-shot basis, facilitating seamless control of operations according to experimental requirements. Using this system, consisting of a linear array of Langmuir probes, measurements of plasma density, temperature, potential, and their fluctuations revealed that the fuel gas-puff impact these mean and fluctuating parameters up to three to four cm inside the LCFS. Attaching an array of magnetic probes to this system led to measurements of magnetic fluctuations inside the LCFS. The HRDS system is fully operational and serves as an important diagnostic tool for ADITYA-U tokamak.

Figures

Figures reproduced from arXiv: 2501.04462 by the authors.

**Figure 2.** (a) CATIA drawing of High-speed Reciprocating Drive System for ADITYA-U tokamak (b)Total Magnetic field in the vicinity of ADITYA-U tokamak (a) Mechanical Supports with Teflon Bushes Port for Pumping D A B C 1 E |B| at Motor Location (2.5 m) ≈ 30 G (b) Moveable clutches [PITH_FULL_IMAGE:figures/full_fig_p005_2.png] view at source ↗

**Figure 3.** Schematic for HRD System Operation FESTO make controller CMMP-AS-C5-11A-P3-M3 is used for operating the motor, this controller essentially requires main power switch, circuit breaker for protection, and power supply (24 V) for control section, holding break and I/O, comprehensive pinout diagram can be found in reference [29]. The controller is connected to a NI-PXI (National Instruments PCI eXtensions for Instrument… view at source ↗

Figures from the paper (3 more)

**Figure 4.** Figure 4: (a) servo motor-integrated mechanical setup of the HRDS (b) Schematic of laser and photodiode assembly used for speed measurement (c) Signal from photo diode 1 at 0 cm (red solid) and photo diode 2 at 5 cm (black dotted) (d) LP design (e) Magnetic probe (f) Magnetic pr…

**Figure 5.** Figure 5: (a) the schematic of probe motion in GDC plasma, (b) floating potential measured from reciprocating LPs in GDC plasma To achieve the primary goal of investigating the effects of gas-puffing on edge plasma turbulence and spatial profiles, the HRDS is installed on ADITYA…

**Figure 6.** Figure 6: Comparison between plasma parameters discharge #36968 (magenta solid) and #37012 (Black dotted) (a) loop voltage (VL); (b) plasma current (Ip); (c) H-alpha emission intensity (𝐻𝛼);(d) soft X-ray emission intensity (SXR);(e) poloidal magnetic field oscillations (𝐵̃ 𝜃);(…

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Reference graph

Works this paper leans on

41 extracted references · 41 canonical work pages

[1]

Plasma Discharge Duration: With discharge durations ranging from 100 to 400 ms, the drive mechanism must enable the probe to scan a range of 4 -5 cm within 100 -120 ms, requiring an average probe head velocity of 0.4-0.6 m/s

work page
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Mechanical Design of HRDS for ADITYA-U: Designing a multi-purpose reciprocating drive system for complex machines like tokamaks poses number of challenges, with each machine imposing its own unique set of requirements. Key factors that vary between tokamaks include the availability of space, particularly concerning port location and size, the duration of ...

work page
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Ultra-High Vacuum Conditions: All components of the system must be compatible with ultra-high vacuum (UHV) conditions (10⁻⁸ Torr), with a permissible leak rate as low as 10⁻¹⁰ mbar·l/s to maintain the integrity of the overall vacuum environment of ADITYA-U

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This demands usage of gate-valve and bellow with higher stroke lengths for effective operation

Probe Head Flexibility and Stroke Length: The system should allow easy replacement of probe heads based on experimental requirements, i.e., without affecting the overall system vacuum, along with a mechanism for replacing damaged probes. This demands usage of gate-valve and bellow with higher stroke lengths for effective operation

work page
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Mechanical Structure and Load Capacity: The structure must be designed to support a total weight of 45 kg, with sufficient strength to handle the momentum of the probe assembly, which reaches approximately 10 kg·m/s

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A user -friendly interface must allow operators to pre-program parameters such as speed, acceleration, and scan length for the HRDS

Remote Control and User Interface: Given restricted access to the tokamak hall during operations, remote control of the drive system is essential. A user -friendly interface must allow operators to pre-program parameters such as speed, acceleration, and scan length for the HRDS

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Durability and Maintenance of Probe Heads: Probe heads must be capable of withstanding high-temperature plasma environments and feature a modular, easy-to-assemble design for rapid replacement in the event of damage, ensuring minimal disruption to experime ntal operations

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P” m, the effective radius, “rm

Issues with stray magnetic fields: The driving motor needs to be protected from the stray magnetic field present in the vicinity of the tokamak during operation. 5 Meeting these requirements is essential to ensure the system operates effectively and experimental explorations of gas puff induced edge plasma dynamics is possible. Considering the above - men...

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Operation of HRDS assembly and Probe head designs: After assembling all the components of HRDS and integrating the servo motor (as shown in Figure 4a), several dedicated test runs have been conducted to ascertain the desired vacuum sealing and high-speed motion of the shaft un...
[10]

Operation of HRD system with plasma: The HRD system has been installed in the ADITYA -U tokamak with LP -head meeting all the vacuum requirements of the tokamak system. Before operating the HRD system in the tokamak plasma, its operation has been tested in continuous glow-disc...
[11]

Effect of gas-puffs on edge plasma dynamics: After thoroughly testing the HRDS system and ensuring the negligible impact of probe -head movement using HRDS on the plasma, the effect of gas -puffing (injection of short bursts of fuel gas) on edge plasma parameters are studied [...
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Brunner, A

D. Brunner, A. Q. Kuang, B. Labombard, and W. Burke, Linear servomotor probe drive system with real-time self-adaptive position control for the Alcator C-Mod tokamak, Rev. Sci. Instrum. 88, (2017)

2017
[40]

Pandey et al., Pop-up Langmuir probe diagnostic in the water cooled divertor of Wendelstein 7-X, Rev

A. Pandey et al., Pop-up Langmuir probe diagnostic in the water cooled divertor of Wendelstein 7-X, Rev. Sci. Instrum. 95, (2024)

2024
[41]

Festo Configuration Tool - PlugIn CMMS-ST, (n.d.)

Pith tools

Reviewed August 10, 2026 · model on record in the stance chip above.

[1] [1]

Plasma Discharge Duration: With discharge durations ranging from 100 to 400 ms, the drive mechanism must enable the probe to scan a range of 4 -5 cm within 100 -120 ms, requiring an average probe head velocity of 0.4-0.6 m/s

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[2] [2]

Mechanical Design of HRDS for ADITYA-U: Designing a multi-purpose reciprocating drive system for complex machines like tokamaks poses number of challenges, with each machine imposing its own unique set of requirements. Key factors that vary between tokamaks include the availability of space, particularly concerning port location and size, the duration of ...

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[3] [3]

Ultra-High Vacuum Conditions: All components of the system must be compatible with ultra-high vacuum (UHV) conditions (10⁻⁸ Torr), with a permissible leak rate as low as 10⁻¹⁰ mbar·l/s to maintain the integrity of the overall vacuum environment of ADITYA-U

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[4] [4]

This demands usage of gate-valve and bellow with higher stroke lengths for effective operation

Probe Head Flexibility and Stroke Length: The system should allow easy replacement of probe heads based on experimental requirements, i.e., without affecting the overall system vacuum, along with a mechanism for replacing damaged probes. This demands usage of gate-valve and bellow with higher stroke lengths for effective operation

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[5] [5]

Mechanical Structure and Load Capacity: The structure must be designed to support a total weight of 45 kg, with sufficient strength to handle the momentum of the probe assembly, which reaches approximately 10 kg·m/s

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[6] [6]

A user -friendly interface must allow operators to pre-program parameters such as speed, acceleration, and scan length for the HRDS

Remote Control and User Interface: Given restricted access to the tokamak hall during operations, remote control of the drive system is essential. A user -friendly interface must allow operators to pre-program parameters such as speed, acceleration, and scan length for the HRDS

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[7] [7]

Durability and Maintenance of Probe Heads: Probe heads must be capable of withstanding high-temperature plasma environments and feature a modular, easy-to-assemble design for rapid replacement in the event of damage, ensuring minimal disruption to experime ntal operations

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[8] [8]

P” m, the effective radius, “rm

Issues with stray magnetic fields: The driving motor needs to be protected from the stray magnetic field present in the vicinity of the tokamak during operation. 5 Meeting these requirements is essential to ensure the system operates effectively and experimental explorations of gas puff induced edge plasma dynamics is possible. Considering the above - men...

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