We want to measure thrust on an independent stand to confirm performance of our RF ion thruster. Therefore, we're looking for a place to measure thrust in a vacuum chamber with device for measuring thrust in the range from 1 to 10 mN.
The target specifications of our propulsion system: thrust 5mN, specific impulse 2000s, the total power consumption of up to 250W and mass 8 kg.
You can also contact Sital SpA (Pisa) and Aerospazio Tecnologie Srl in Italy.
We could do this as we have adequately fitting thrust balances. However, can you say some words on propellant, mass flow rate and RF-Interfacing?
During the important direct measurements of the thrust for your RF ion thruster, (for which, as Georg said, I would like to obtain further information on propellant, mass flow rate and RF-Interfacing etc.) I recommend to measure also the ionizati on percentage using results from OES. I am very interested on such experimental work, for which I could provide the necessary theoretical ionization percentage and line intensities, coming from a dedicated Detailed Global Model (DGM) developed by DEDALOS.
We want to make control measurements of thrust outside our laboratory in early 2020. Our laboratory model produces around 1-9 mN (control points 5 and 7 mN) of thrust at 100-300W power consumption at a frequency of 1- 6 MHz and a flow rate of 1-4 sccm (Xe). Our RF generator is a vacuum version and has standard electrical inputs (not coaxial RF input). The effects of various factors (generator power and frequency, mass flow, discharge chamber shape, magnetic field, etc.) are being investigated in the model lab frame. A numerical plasma model is also being formulated, the results of which will be verified using a three-electrode Langmuir probe (inside the discharge chamber) and a Faraday probe (measuring the ion beam).
Konstantinos Katsonis , We have no experience with spectroscopy, but it would be interesting to do. We are open to any interactions and research.
We have, in DEDALOS, a long experience with optical emission spectroscopy, both with plasma spectra acquisition and with evaluation of the theoretical line intensities. For the former, a spectrometer and an optical window are the basis. For the latter, specific Detailed Global Models (DGM) for various propellants are part of our heritage. Indeed, besides providing an information on the thruster plasma constitution and ionization, DGMs give the necessary theoretical intensities to compare with the experimental ones in order to diagnose through OES. DGMs replace advantageously the C-R models in case of confined plasma of the type encountered in plasma thrusters, giving also a detailed description of the power losses due to various mechanisms.
Chloe Berenguer I am very interested in DGM method, is there any literature recommended? Thx.
Yes. A spectroscopic assessment would be beneficial. The question is how to proceed now.
Yanan Wang About DGM literature, there is a lot of papers contained in RG projects by Konstantinos Katsonis and myself, which you could consult cost free.
Of course, the dedicated DGM of primary interest to you depends on the propellant you are interested in.
Re to Ruslan Rakhimov question about optical spectroscopy diagnostics, we at DEDALOS are interested in characterizing thruster prototypes by means of adequate spectra acquisition and collaborate in related scientific projects. As Georg Herdrich was saying, information about Xe mass flow rate and RF-Interfacing which you are using / considering could be welcome for the necessary tunning.
Besides using our XeDGM, we have made spectral acquisitions in the past and we could help you on that. Do you have any spectrometer at hand and is there a port in the vacuum vessel in order to capture the emission spectrum ? Let us know about !
Konstantinos Katsonis
By the end of the year we will have a vacuum generator. In this case we will need to enter only DC to power the generator. But if we don’t have a vacuum generator ready, we can use our atmospheric generator, for this we need an RF input (coaxial input, or copper pins with a cross section of more than 8 mm. In this case, the losses will be about 2-3W). Also, we can easily adapt our design to any input.
Xenon mass flow rate: 1-3 sccm.
At the moment, we haven’t any equipment for plasma spectroscopy. But we are interacting with Bauman University (Russia). If you give equipment requirements, we will search.
What kind of object are you interested in? Is it plasma in the discharge chamber or is the ion beam leaving the thruster?
The discharge chamber is made of ceramic and closed with perforated grids. This makes access to plasma difficult.
Ruslan Rakhimov In fact, the whole procedure is somehow described in our paper K. Katsonis, Ch. Berenguer, D. Pavarin , F. Trezzolani, M. Manente, J. Gonzalez del Amo, A Xenon Detailed Global Model in Support of Electric Propulsion Technology, 6th Space Propulsion Conference, Paper ID SP2018_212, Seville, Spain, May 2018, which has been made available recently at RG. There is not any special requirement for the spectrometer, it has only to be able to obtain quite precise spectra in the 460 nm – 545 nm region, as those shown in the paper, plus roughly in the 600 nm – 850 nm in order to get an inspection of the Xe I spectrum. An optical fiber (and collimator) will also be needed.
As it is cumbersome to obtain spectra inside the thruster, a spectrum centered just in its exit will do. For more information, your laboratory should contact me directly through my email, which I will send you personally.
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