• Journal of the Korean Society of Propulsion Engineers
• /
• v.20 no.3
• /
• pp.54-62
• /
• 2016

Micro plasma thruster (${\mu}PT$) was studied experimentally with a dual-stage micro-hollow cathode discharge (MHCD) plasma. Electrostatic-like acceleration exhibiting more directional and elongated exhaust plume was achieved by a dual layer MHCD at the total input power less than 10 W with argon flow rate of 40 sccm. V-I characteristic indicated that there was an optimal regime for dual-stage operation where the acceleration voltage across the second stage remained constant. Estimated exhaust plume length showed a similar trend to the analytic estimate of exhaust velocity which scales with an acceleration voltage. ${\mu}PT$ with multiple holes exhibited similar performance with single-hole thruster indicating that higher power loading is possible owing to decreased power through each hole. Boltzmann plot of atomic argon spectral lines showed average electron excitation temperature of about 2.6 eV (~30,170 K) in the exhaust plume.

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2011.11a
• /
• pp.540-543
• /
• 2011

This work is devoted to an experimental investigation on conceptual design of dual consecutive stage micro plasma thruster (${\mu}PT$). Optimization study on the thruster configuration has been performed for various electrode gap distances from 1 mm to 2 mm and the hole diameter from 0.3 mm to 2 mm depending on desired operating conditions and corresponding nozzle design requirement. The operation of ${\mu}PT$ at low pressure from $10^{-1}$ Torr to $10^{-4}$ Torr and at various argon flow rates ranging from 5 sccm to 300 sccm has been studied to understand the physic of plasma and the gas dynamics in details. The specific impulse can reach up to 3000-4000 seconds at low power consumptions from 1 to 5 W. Image of exhaust plume from ${\mu}PT$ will be provided and electrical characteristics is also mentioned in this paper.

• Bulletin of the Korean Space Science Society
• /
• 2007.10a
• /
• pp.139-143
• /
• 2007

Electric propulsion has become a cost effective and sound engineering solution for many space applications. The success of SMART-1 and MUSES-C developed by European Space Agency (ESA) and Japan Aerospace Exploration Agency (JAXA) each proved that even small spacecraft could accomplish planetary mission with electric propulsion systems. A small electric propulsion system which is Hall effect thruster like SMART-1 is under development by SaTReC and GDPL (Glow Discharge Plasma Lab.) in KAIST for the next microsatellite, STSAT-3. To achieve optimized propulsion system, it is very necessary to understand plasma motions of Hall effect thruster. In this paper, we try to approach comprehensive plasma model with the particle simulation complementary to Particle In Cell (PIC) simulation. We think these two different approaches will help experimenters to optimize Hall effect thruster performances.

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2009.05a
• /
• pp.365-368
• /
• 2009

A new concept of a small thruster for altitude control of a micro/nano class satellite is developed, which utilizes the pulsed laser energy. As the laser-based thruster does not require burning of any fuel, it gives promise of small satellite design criteria, namely light weight and cost effectiveness. In this paper, we develop gel-type material for generating strong plasma plume for enhancing thrust for propulsion. Moreover, we quantify the level of thrust via the momentum coupling coefficient measured by the pendulum system. We discover that the driving force is significantly improved via the gel-typed propellant for laser ablation.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.37 no.2
• /
• pp.175-180
• /
• 2009

In this article, we fabricated polytetrafluoroethylene(PTFE) nozzle treated by ion beam, in order to fabricate polymer based electrospray micro thruster with super hydrophobic nozzle. To obtain the super hydrophobic surface, PTFE surface is treated by argon and oxygen plasma treatment process. The optimal condition is investigated argon and oxygen flow rate as well as the paalied energy level for the treatment process. Fabricated nozzle was evaluated by measuring contact angle, and the surface morphology was examined by using scanning electron microscope(SEM) and atomic force microscope(AFM). We observe that jetting becomes more stable and repeatable on the treated nozzle. And to evaluate performance of fabricated nozzle, we measure micro scale thrust using a cantilever and a nozzle treated by ion beam laser displacement sensor.

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2004.03a
• /
• pp.271-277
• /
• 2004

As one of the concepts of the laser/electric hybrid propulsion system, a feasibility study on possibilities of electrostatic acceleration of a laser ablation plasma induced from a solid target was conducted. Energy distributions of accelerated ions were measured by a Faraday cup. A time-of-flight measurement was also conducted for ion velocity measurement. It was found that an average speed of ions from a pure laser ablation in this case was about 20 km/sec for pulse energy of 40 $\mu$J/pulse with pulse width of 250 psec. On the other hand, through an electrostatic field with a + I ,000 V electrode, the speed could be accelerated up to 40 km/sec. It was shown that the electrode with positive potential was more effective than that with negative potential for positive-ion acceleration in laser induced plasma, or pulsed plasma, in which ions were induced with the Coulomb explosion following electrons. In addition, the ion-acceleration or deceleration strongly depended on conditions of pairs of inner diameter and electrodes gap.

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2004.03a
• /
• pp.588-592
• /
• 2004

This paper presents the preliminary fabrication results of colloid thrusters which can provide thrust of the order of micro to milli-Newtons. MEMS technology has been used for fabrication, and four essential fabrication techniques - deep etching with nested masks, isotropic plasma etching, anisotropic reactive ion etching, and direct fusion wafer bonding - have been newly developed. Among diverse models which have been designed and fabricated, the fabrication results of 4-inch wafer-based colloid thrusters are presented.

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2008.03a
• /
• pp.877-880
• /
• 2008

In this article, in order to fabricate polymer based electrospray device with super hydrophobic nozzle we use PTFE(polyfluorotetraethylene) plate and PMMA(polymethylmethacrylate). To obtain the super hydrophobic surface nozzle, PTFE surface is treated by argon and oxygen plasma treatment process. And evaluate the treated surface, perform measuring contact angle, SEM(Scanning Electron Microscope) and AFM(Atomic Force Microscope). We compare the performance of the super hydrophobic PTFE surface nozzle with raw PTFE and PMMA surface nozzle. For the ion beam treated PTFE nozzle, the liquid doesn't overflow and it keeps initial position and meniscus shape. From these results, we expect in cease of superhydrophobic surface nozzle jetting becomes more stable and repeatable.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.33 no.3
• /
• pp.93-98
• /
• 2005

STSAT-2 will be launched on December 2007 by the first Korean launch vehicle KSLV-1, and its one of the main instruments is DREAM (Dual Channel Radio Frequency and Environment Atmosphere Monitoring) which detects a signal for atmosphere from the Earth by using micro-wave signal. The STSAT-2 has many units for technology demonstration such as FDSS (Fine Digital Sun Sensor) and DHST (Dual Head Star Tracker) including PPT (Pulsed Plasma Thruster) for attitude control and momentum dumping in the space. In this paper, the power budget analysis for STSAT-2 will be studied and provided for supporting the whole mission life time during the mission of its spacecraft.