Plasma characterization in CW and pulsed mode and its effect on beam current in 2.45 GHz ECR Ion source

Kewlani, Hitesh; Gharat, Surendra; Roychowdhury, P.; Dikshit, Biswaranjan

doi:10.1088/1748-0221/17/09/p09016

Cited by 3 publications

(4 citation statements)

References 21 publications

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“…The optimized operating gas pressure during this experiment is 2.4 mTorr. The wave cut-off probe results show that, even at low input MW powers the plasma density is comparable with the LEHIPA ECR-IS which operates at > 1 kW MW power [29]. This clearly points at the better coupling of MW to the plasma chamber with optimized one step ridge coupler.…”

Section: Plasma Studiesmentioning

confidence: 78%

Tailoring of microwave power density in an ECR ion source using an optimized ridge coupler

Phogat,

Mathew

2023

Phys. Scr.

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One of the interesting areas in the Electron Cyclotron Resonance Ion Source (ECR-IS) design which requires further exploration is the microwave power launching scheme and the power coupling optimization with the plasma chamber. The electron heating efficiency and thereby the plasma density highly depends on the electric field distribution inside the plasma chamber; therefore, it is important to optimize the coupling of microwave power to the plasma chamber, to maximize the electric fields in the plasma chamber for a given microwave power. For this, a single-step quarter wavelength ridge coupler design study has been carried out using CST MW Studio Suite along with the plasma chamber and ridge wave guide designs. The experimental measurements of electric and magnetic field profiles in the plasma chamber assembly with different coupling configurations have been done using an innovative bead pull technique and a magnetic field probe. The experimental results match well with the simulation results and the comparative studies of different coupling configurations reveal that the single step ridge coupler based scheme improves the electric field inside the plasma chamber to at least five times than the conventional ridge waveguide. To further improve the E-field amplitude in the plasma chamber by another 40 %, a novel tuning scheme for the coupler has been introduced. Preliminary plasma studies have been carried out with the optimized coupler on a multicusp ECR plasma source and the plasma density measurements performed using a microwave cut-off probe. The plasma measurements show that even at low input microwave powers (~ 300 W) the plasma density is comparable with standard ECR-IS. The present study thus, sheds light on the coupling configuration of microwave to plasma chamber with experimental measurements of cavity mode and fields in the cavity which will be useful for high intensity accelerator applications in understanding the plasma evolution, beam parameters and its dependence on different operating parameters.

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Section: Plasma Studiesmentioning

confidence: 78%

Tailoring of microwave power density in an ECR ion source using an optimized ridge coupler

Phogat,

Mathew

2023

Phys. Scr.

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“…An upgraded 2.45 GHz ECR ion source test bench has been designed and developed to achieve beam current in the range of ∼ 10-15 mA, beam emittance ∼ 0.2 𝜋•mm•mrad and proton fraction of > 80% requested by the LEHIPA. The first stage is the analysis of ECR plasma using the Langmuir Probe [9], the second stage is the analysis of pulsed ion beam extraction approaches [10]. This paper discusses proton fraction characterization using an analyzing magnet and its enhancement.…”

Section: Introductionmentioning

confidence: 99%

An experimental investigation of the proton fraction in a three electrode 2.45 GHz ECR ion source

Kewlani,

Gharat,

Roychowdhury

et al. 2024

J. Inst.

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The ion beam extracted from a proton ion source contains H+ ion along with H2 + and H3 + molecular ions. In this work, the ionic fractions in the extracted beam of ECR ion source were measured using an analyzing magnet. A computerized proton fraction measurement setup is described in detail with instrumentation and control for pulsed operation of the ECR ion source. A timing diagram has been incorporated for trigger synchronization illustrating the process of pulsing the plasma, controlling the analyzing magnet parameters and acquiring data about the magnetic field and beam current. The proton fraction was measured in two cases, in the first case using SS304 plasma chamber and in the second case incorporating aluminium (Al) cylinder and boron nitride (BN) plates inside the plasma chamber. In the first case, the proton fraction was found to be in the range of ∼60% and in the second case because of the presence of secondary electron donors it increased to 93%. In order to understand the enhancement of H+ fraction in the hydrogen plasma, plasma parameters (ne , Te and EEDF) and its dependence on microwave power and neutral gas pressure were investigated.

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“…Standard techniques that are used to map the beam phase space are pepper pot, slit wire scan, Allison scanner etc [16][17][18]. Tomographic phase space reconstruction is an alternative technique which remains unique among these spacious measurement setups since it requires just a single wire/slit scanner in the beam transport line in combination with a magnetic focusing element like solenoid or quadrupole.…”

Section: Introductionmentioning

confidence: 99%

“…Although the tomography method shares similarities with the solenoid/quadrupole scan method, there are notable distinctions between the two approaches. In the solenoid scan method, only the root mean square (rms) beam sizes are utilized and hence the phase space distribution cannot be generated [18][19][20][21]. In addition, this analysis uses a thin lens approximation for the solenoid magnet and hence the emittance values may be better than the actual.…”

Section: Introductionmentioning

confidence: 99%

Phase space reconstruction technique for beam optimization in the Low Energy High Intensity Proton Accelerator (LEHIPA)

Priyadarshini,

Mathew,

Mathad

et al. 2024

Phys. Scr.

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The Low Energy High Intensity Proton Accelerator (LEHIPA) has been commissioned to the design energy of 20 MeV at BARC, India. The low energy beam transport (LEBT) channel of LEHIPA consists of two solenoids and drift spaces for matching the 50 keV proton beam from the ECR ion source (ECR-IS) to the RFQ. The ion beam extracted from the ECR-IS also contains molecular species like H2+ and H3+. Proton fraction in the beam is found to degrade slowly with time due to surface contamination of the plasma chamber and this reduction in proton beam current has implications for longitudinal and transverse beam dynamics. Hence, it becomes important to characterise the beam at different proton fraction levels to understand the end-to-end beam dynamics of LEHIPA. Computed Tomography (CT) technique has been used for the beam phase-space reconstruction in LEHIPA, using a Python program, incorporating the feature of filtering secondary species from the beam profiles measured using slit scanners in the LEBT. Simultaneous Algebraic Reconstruction Technique (SART) is used in the reconstruction since it is identified to be a better technique for a limited number of projections. The reconstruction program is benchmarked with the TraceWin beam dynamics code and implemented on the measured beam profiles to recreate the phase space distribution at the beginning of LEBT. Further, the tomographic reconstruction method is compared with the solenoid scan method and the rms emittance values are found to be in good agreement. The measured tomographic phase space distribution has then been used as TraceWin input for LEHIPA end-end beam dynamics simulations and the LEHIPA beam line parameters are re-optimized for minimum beam emittance growth. This paper presents the simulations of CT technique, benchmarking simulations with TraceWin, phase space reconstruction with measured beam profiles and beam dynamics studies of LEHIPA using the reconstructed beam distributions.

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Plasma characterization in CW and pulsed mode and its effect on beam current in 2.45 GHz ECR Ion source

Cited by 3 publications

References 21 publications

Tailoring of microwave power density in an ECR ion source using an optimized ridge coupler

Tailoring of microwave power density in an ECR ion source using an optimized ridge coupler

An experimental investigation of the proton fraction in a three electrode 2.45 GHz ECR ion source

Phase space reconstruction technique for beam optimization in the Low Energy High Intensity Proton Accelerator (LEHIPA)

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