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About PCARF

The Planetary Cloud/Aerosol Research Facility (PCARF) is a specialized chamber designed to study the processes of aerosol and cloud formation in our solar system and exoplanets. Housed within a 10-foot diameter vacuum chamber at NASA Jet Propulsion Laboratory, PCARF enables controlled experimental investigations of the planetary atmospheric conditions.

The sun's glint beams in between a cloudy stretch of the south Atlantic Ocean off the coast of Argentina.

Motivation

PCARF is designed to enable the scientific experimental investigation of aerosol processes, with a focus on understanding how planetary atmospheric aerosols form clouds and evolve within our solar system and on exoplanets. While existing chambers are primarily dedicated to studying cloud formation processes on Earth, PCARF extends the range of temperature, pressure, and gas compositions to replicate conditions found in the cloud regions of other planets.

The complexity of cloud formation involves numerous interacting processes as illustrated in the following diagram.

Diagram of the numerous interactions experienced by cloud formation processes.

The experimental aims to complement, validate and corroborate current and future research into planetary aerosols conducted through:

  • Computational modeling
  • Experimental chemistry
  • Remote observations
  • In situ measurements
Cloud chambers provide additional data for other types of research into cloud formation processes.

About the Facility

PCARF is a stand-alone assembly housed within the JPL’s 10-foot diameter vacuum chamber, featuring the following specifications:

  • Dimensions: 2 meters in diameter and 3 meters tall, with a total volume of 9 cubic meters.
  • Three distinct temperature zones: the bottom plate, top plate, and the lateral walls. Each section of the chamber is independently controlled.
  • The chamber accommodates 14 ports with a 6-inch diameter, 2 ports with an 8-inch diameter, and 2 ports with a 10-inch diameter.

Chamber Operational Capabilities

  • Temperature range: -180° to +125°C
  • Pressure range: 1 μbar to 1 bar
  • Ambient gases: N2, CO2, and He/H2
  • Various trace gases
Schematic of planetary cloud chamber physical layout. A 6-foot tall person model is included for scale. The schematic illustrates the inner blue cylinder as the cloud chamber and the outer gray cylinder as the 10-foot vacuum chamber, with various floors around the facility.

PCARF Instrumentation

Purpose: to quantify the chemical composition and microphysical property of planetary atmosphere.

PCARF will be equipped with a suite of instruments to quantify the following observables:

  1. aerosol size distribution
  2. aerosol number density
  3. aerosol optical properties
  4. aerosol chemical composition
  5. particle velocity and trajectory during cloud formation and evolution
  6. number density and optical properties of trace gases

Additional features include temperature sensors, pressure sensors, humidity sensors, particle imaging, and particle sampling capabilities.

Block diagram of the planetary cloud chamber showing connections to each of the supporting subsystems associated with the cloud chamber.

The instruments, their related observables, and their data acquisition technique are summarized in the following table.

INSTRUMENTOPSSMPSGAMSPIVFTIR
Data Acquisition TechniqueIn situIn situIn situRemote
sensing		Remote
sensing
Aerosol size distribution✔✔✔
Aerosol number density✔✔✔✔
Aerosol optical properties✔
Aerosol chemical composition✔✔
Particle velocity and trajectories during
cloud formation and evolution		✔
Number density and optical properties of
trace gases		✔

Instrument Descriptions and Capabilities

Optical Particle Spectrometer (OPS)

Purpose: to quantify size distribution and number density of large aerosols [greater than 1 micrometer]

Model: Promo 3000 System Unit Controller, Welas 2100 HP sensor head

Measurement type: In-situ

Capabilities:

  • The OPS sensor is equipped with a versatile inlet system capable of collecting aerosol samples across a wide range of atmospheric conditions.
  • Pressure range: 0.2 to 10.0 bar
  • Temperature range: -130 to +120 ºC
  • The sensor features corrosion-resistant components and a specialized cuvette for enhanced durability in harsh environments.

Aerosol sizing and counting:

  • Particle size range: 0.5 to 100 micrometers with up to three selectable measuring ranges: [0.3 to 10] µm, [0.3 to 17] µm, [0.6 to 40] µm.
  • Concentration range: Up to 106 particles/cm3
  • For concentrations of 2.0×105 particles/cm3 or higher, the system can reliably measure aerosol concentrations on a 1-second basis.
Image of Optical Particle Spectrometer Instrument
Image of Optical Particle Spectrometer Instrument, courtesy of Palas, used with permission.

    Scanning Mobility Particle Sizer (SMPS)

    Purpose: to quantify size distribution and number density of small aerosols measuring less than 1 micrometer in diameter.

    Model: TSI SMPS 3938

    Measurement type: In-situ

    Capabilities:

    • The SMPS is designed for high-precision aerosol sizing and counting, covering a particle size range from 10 nm to 1 micrometer. With additional components, capabilities can extend down to 1 nm.
    • Pressure range: 0.7 to 1.25 bar,
    • Temperature range: 10℃ to 40℃
    • The sensor features 128 size channels within the measuring range for detailed analysis.

    Measurement sequence:

    The SMPS operates through a 4-step process involving three subsystems:

    • Large particle removal: filters out particles larger than 1 micrometer
    • Charge conditioning
    • Particle sizing
    • Aerosol concentration measurement
      Image of Scanning Mobility Particle Sizer instrument
      Image of Scanning Mobility Particle Sizer instrument, courtesy of TSI Inc, used with permission.

      Gas and Aerosol Separator Mass Spectrometer (GAMS)

      Purpose: to quantify the chemical composition of planetary atmospheres, particularly in challenging environments like those containing sulfuric acid aerosols.

      Development: JPL/NASA project led by Principal Investigators: Dragan Nikolic and Stojan Madzunkov.

      Capabilities:

      • The GAMS can perform a broad range of in-situ measurements, offering speciation and quantification of trace gases and aerosols in harsh conditions.
      • Pressure range: 0.01 to 60 bar
      • Temperature range: – 40 ℃ to 80 ℃

      Measurement details:

      Provides speciation and quantification of trace gases and aerosols.

      • Detects species within the range of 1-150 amu.
      • Achieves a precision of 20% within 0.5 hour for any species with concentration as low as 50 ppb.
      • Measures the chemical composition of aerosols smaller than 10 microns.
      • Features an Advanced Aerosol Inlet (AAI) module that separates aerosols from trace gases.
      • Utilizes a Quadruple Ion Trap Mass Spectrometer (QITMS).
      GAMS Instrument Schematic: 1. Piezo valve inlet with gas feed, 2. Aerosol separator with Differential Pump System (DPS), 3. Aerosol vaporizer, 4. Quadrupole Ion Trap Mass Spectrometer Chamber, 5. Vacuum chamber, 6. Ion/getter pump, 7. Electronics, 8. Gate Valves, 9. Turbo drag vacuum pump.

      Particle Image Velocimetry (PIV)

      Purpose: to capture both large- and small-scale particle motion, providing detailed analysis of the flow field. The system uses a pulsed laser and light sheet optics to capture images of seeding particles and measures flow fields by cross-correlating pairs of images.

      Model: 2D3C PIV LaVision, offering 2D imaging with 3 velocity components using a dual-camera assembly within the light sheet.

      • Direct tracking of particles 0.5 micron or larger, allowing for real-time observation of condensation processes.
      • Two lens configurations enable flexible analysis, accommodating both large scale and small-scale flow dynamics.
      • The system operates with a laser pulse rate of 15 Hz, ensuring high temporal resolution in capturing rapid flow events.
      Animated image of Particle Image Velocity Instrument System, courtesy of LaVision, used with permission.

      Fourier Transform Spectrometer for the Infrared (FTIR)

      PURPOSE: to quantify the chemical composition and microphysical property of trace gases and aerosols. The system uses white mirror cells to achieve long path lengths from 12 to 150 meters, enabling precise observations of trace gas concentrations, as well as particle composition, size, and shape.

      Model: Nicolet iG50 or iS50 Standard Mid-IR Spectrometer equipped with a KBr beamsplitter and MCT detector.

      Capabilities:

      • Direct tracking of particles 0.5 micron or larger, allowing for real-time observation of condensation processes.
      • Two lens configurations enable flexible analysis, accommodating both large scale and small-scale flow dynamics.
      • The system operates with a laser pulse rate of 15 Hz, ensuring high temporal resolution in capturing rapid flow events.
      Image of Nicolet(TM) iS50 FTIR Spectrometer, courtesy of Thermo Fisher Scientific
      Image of NicoletTM iS50 FTIR Spectrometer, courtesy of Thermo Fisher Scientific, used with permission.
      White cell in AIDA chamber at KIT
      White cell in AIDA chamber at KIT.
      Credit: White, J.U. “Long Optical Paths of Large Aperture,” J. Opt. Soc. Am. 32, 285-288, 1942.
      Photos of M1, M2, and M3 mirrors.
      (Left) M2 & M3 gold coated mirrors. (Right) M1 field mirror.
      Credit: Wagner, R. et al. “Probing ice clouds by broadband mid-infrared extinction spectroscopy: case studies from ice nucleation experiments in the AIDA aerosol and cloud chamber”, Atmos. Chem. Phys., 6, 4775–4800, 2006.