1. Performance of a New Low-Pressure Water-Based CN Instrument - Rogers, Hering, Stolzenburg, Oberreit, Quant - Outline challenge of measuring CNchallenge of measuring CN description of new “gap” instrumentdescription of new “gap” instrument evolution during ProgSci & T-REXevolution during ProgSci & T-REX examples of dataexamples of data June 2006

2. why measure Condensation Nuclei ? characterize the air: clean background or pollutionclean background or pollution identify aerosol plumes air mass tracer identify regions of new particle formation estimate particle scavenging rates by clouds

3. challenge of measuring CN how to cover entire altitude range of HIAPER ? CN instruments common; several commercial vendorscommon; several commercial vendors particles grow in supersaturated butyl alcoholparticles grow in supersaturated butyl alcohol vapor  few µm  counted with OPC lose sensitivity at low pressure (alt > ~10 km)lose sensitivity at low pressure (alt > ~10 km) threshold detection size changes with pressure butanol is toxic and flammablebutanol is toxic and flammable other special-purpose instruments use fluorinertother special-purpose instruments use fluorinert water as active fluid ?water as active fluid ?

4. vapor pressure of water design range

5. based on TSI-3786 aka Aerosol Dynamics / Quant Low-Pressure microprocessor, ethernet, USB, serial 300 ccm, 10 Hz d* ~ 5 nm d* ~ 5 nm

6. flow diagram two pumps, speed control uses feedback from orifice Δp saturate 5°C growth 45°C

7. WCN evolution during ProgSci  T-REX Nov 9 #1 “loaner” delivery (partially modified instrument) Nov 22 – tF01 WCN data kills DSM serial Dec 1 – RF01 Flow not controlling; troubleshoot Dec 7 – RF03 WCN not on HIAPER Dec 8 – RF04 Re-install; flow not controlling Dec 9 – RF05 Remove WCN Dec 16 - RF09 #2 delivery; flow control is good Dec 20 – RF11 “out of water” after 1 hour at 42 kft Feb 16 – tf01 shorter inlet piping; flow control good Feb 22 – tf02 add drain bottle; faster water injection Mar 24 flush orifices; dry out filters

8. RF04 – poor flow control set point 300

9. rf09 – good flow control

10. next ? compile performance history  web sitecompile performance history  web site modifications to firmware  faster water injection ratemodifications to firmware  faster water injection rate delivery of instrument #1 + trainingdelivery of instrument #1 + training compare CN measurements MASS, FCAS, RDMAcompare CN measurements MASS, FCAS, RDMA conference paper - International Aerosol Conf., 13G16 Airborne tests of a new low-pressure water-based CN instrument http://www.aaar.org/meetings/IAC2006/index.htm