The NASA Ames Arc Jet Complex provides ground-based testing of aerothermal environments using arc jet facilities to simulate flight entry conditions for thermal protection materials and hypersonic vehicles. It has seven test bays, including ones with arc jets ranging from 5-75 megawatts, making it the highest power arc jet facility in the world. The complex has supported many NASA programs and is used to test candidate thermal protection systems for up to an hour in conditions simulating atmospheric entry.

1. NASA Ames Arc Jet Complex
Providing ground-based aerothermal environments in support of the Nation’s Research
& Development activities in Thermal Protection Materials, Vehicle Structures, Aerother-
modynamics, and Hypersonics.
Background
Innovative TPS materials and systems will be
required to support the Exploration Initiative.
Project Constellation missions, in particular
crewed Moon or Mars return missions, will
involve high velocity aerocapture or direct
entry at Earth. These high stress missions will
induce heating environments too severe for
existing reusable Thermal Protection Systems
(TPS). Qualifying a new TPS material for a
crewed mission requires extensive testing to
explore the limits of material performance, to
validate reliability and repeat-ability of matrial
responce models, to investigate the effects of
material damage, and to develop a full data-
base of material properties. Arc plasma facili- Thermal Protection test in NASA Ames Arc Jet complex
ties are critical to such a process, and to any
other TPS developments required for Explora-
tion missions, by providing the only ground-
based simulation of flight entry conditions. tion of the gas state before or after the shock
front, the arc jets are providing investigators
Fundamental Research in Hypersonics
with usable test environments that match the
The arc jets provide a hypersonic flow for test- important parameters of hypersonic flow.
ing materials and experimental measurement
Ames Arc Jet Complex
techniques in support of the Fundamental
Aeronautical Research carried on at Ames The Ames Arc Jet Complex has seven
for ARMD. Arc jets are being used to provide available test bays. At the present time,
material response data on new, advanced four bays contain Arc Jet units of differing
TPS concepts being developed at NASA configurations, serviced by common facility
Ames Research Center, other NASA centers, support equipment. These are the Aerody-
Department of Defense, and in private indus- namic Heating Facility (AHF), the Turbulent
try. These materials are at the forefront of Flow Duct (TFD), the Panel Test Facility
concepts for hypersonic entry into planetary (PTF and Truncated PTF), and the Interac-
atmospheres. Additionally, the arc jets have tion Heating Facility (IHF). Two additinal test
proven to be a valuable tool for DARPA and bays are being configured; one supports the
the U.S. Air Force in studies of thermal protec- 5-MW Developmental Arc Jet and the other
tion of hypersonic cruise vehicles. supports a 75-MW Lunar Environmental Arcjet
Facility. The support equipment includes two
NASA Ames arc jets also support sensor
D.C. power supplies (20 MW and 150 MW), a
development and experimental capabilities as
steam ejector-driven vacuum system, a water
part of fundamental research into hypersonic
cooling system, high-pressure gas systems,
entry and basic hypersonic flow. Whether
data acquisition system, and other auxiliary
it is advanced thermometry, recession rate
subsystems.
sensors, pressure sensors, or LIF investiga-
www.nasa.gov

2. The magnitude and capacity of these systems design in 1964 by Stein, Shepard and Watson
makes the Ames Arc Jet Complex unique of NASA Ames produced a high-enthalpy
in the world. The largest power supply can constricted arc heater, which enabled TPS
deliver 75 MW for a 30 minute duration or development for Mercury and Apollo missions.
150 MW for a 15 second duration. This power
capacity, in combination with a high-volume Ames heritage includes the Space Shuttle, Vi-
5-stage steam ejector vacuum-pumping king, Pioneer-Venus, Galileo, Mars Pathfinder,
system, enables facility operations to match Stardust, NASP, X-33, X-34, SHARP-B1 and
high-altitude atmospheric flight conditions with B2, X-37, Mars Exploration Rovers, Phoenix,
samples of relatively large size. and most recently Orion and Mars Science
Laboratory. Such a history has fostered the
The Arc Jet Complex offers unique facilities. growth of extensive local expertise in the
The Interaction Heating Facility (IHF), with an development and refinement of the arc jet
available power of over 60-MW, is one of the facilities. The facilities of the Arc Jet Complex
highest-power arc jets available. It is a very are used to simulate the aerothermodynamic
flexible facility, capable of long run times of up heating that a spacecraft endures throughout
to one hour, and able to test large samples in atmospheric entry, and to test candidate TPS
both a stagnation and flat plate configuration. materials and systems. The duration of such
The Panel Test Facility (PTF) uses a unique testing can range from a few seconds to more
semielliptic nozzle for testing panel sections. than an hour, and from one exposure to mul-
Powered by a 20 MW arc heater, the PTF can tiple exposures of the same samples.
perform tests on samples for up to 20 min-
utes. The Turbulent Flow Duct (TFD) provides
Arc Heater
supersonic, turbulent high-temperature air
flow over flat surfaces. The TFD is powered
by a 20 MW Hüls arc heater and can test An arc jet is a device in which gases are
samples 203 mm by 508 mm in size. The heated by a DC electric arc discharge and
Aerodynamic Heating Facility (AHF) has expanded to very high temperatures (greater
similar characteristics to the IHF arc heater, than 6000K). The gases (typically air) pass
offering a wide range of operating conditions, through a supersonic/hypersonic nozzle
samples sizes and extended test times. A aimed at a test sample in vacuum, and flow
cold-air-mixing plenum allows for simulations over it, producing a reasonable approxima-
of ascent or high-speed flight conditions. tion of the surface temperature, pressure, and
Catalycity studies using air or nitrogen can the gas enthalpy experienced by a vehicle on
be performed in this flexible arc heater. A atmospheric entry.
5-arm model support system allows the user
to maximize testing efficiency. The AHF can Website
be configured with either a Hüls or segmented
http://thermo-physics.arc.nasa.gov
arc heater, up to 20-MWs.
History
The Ames Arc Jet Complex has a rich heri-
tage of over 40 years in Thermal Protection
System (TPS) development for every NASA
Space Transportation and Planetary programs
including Apollo. The Ames Arc Jets began
in the 1950’s with the founding of a perma-
nent facility in 1961. A breakthrough patented
National Aeronautics and Space Administration
Ames Research Center
Thermophysics Facilites Branch
Moffett Field, CA 94035-1000
NASA Facts
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