Safety Using Fluorine Eximer Lasers Jack J Hahn

Safety Using Fluorine Eximer Lasers Jack J. Hahn SLAC

Purpose of Today’s Talk Background on fluorine gas (F 2) in Eximer Lasers at SLAC n Review hazards of F 2 gas n Worst case accident scenarios n SLAC ES&H Guideline “Safety Using Fluorine Eximer Lasers” n Equipment design approaches to minimize the hazards of F 2 in Eximer Lasers n Not covering laser beam/electrical other hazards n

Background on use of Fluorine in Eximer Lasers at SLAC n Final Focus Test Beam (FFTB)- GAM, Historical Usage n n Fringe patterns to measure beam location Klystron Test Laboratory- Lambda Physik n Laser beams to make plasma deposited oxide cathodes

Final Focus Test Beam

Klystron Test Lab Laser

What is a Fluorine Eximer Laser? n Uses “Excited Dimer” lasing medium n Excited diatomic molecule- Inert gas/halogen n Halogen is Fluorine

Some Hazards of Pure Fluorine Gas n Reacts violently and decomposes to hydrofluoric acid (HF) with moisture n Fire fighting- Fires with fluorine as oxidizer only extinguished by shutting off source of fluorine. Water, CO 2 add fuel to fire n Immediately dangerous to life and health (IDLH) = 25 ppm

Forms of Fluorine Used n FFTB GAM 1700 ppm premix of F 2 n 5% F 2 Passivating Gas n n Lambda Physik n Pure F 2 generated where needed

Worst Case Accident Scenarios n Whole-bottle 5% F 2 passivating gas release in FFTB n 300 yard FFTB area- 3 times FFTB area is affected > IDLH. Unacceptable, required mitigation. (credit to Joe Kenny/Ih Lin for these calculations)

SLAC ES&H Guideline “Safety Using Fluorine Eximer Lasers” n Networking from International HEP Safety Forum n Charles (Bill) Nuttall (CERN retired); Joe Kenny, Dr Maria Gherman, John Shepardson n Hazardous Experimental Equipment Committee (HEEC) all of SLAC

SLAC ES&H Guideline (cont. ) n Other influences n Santa Clara County Toxic Gas Ordinance n n http: //www. ehinfo. org/content/0, 4745, sid%253 D 11383%2526 chid %253 D 15213%2526 ccid%253 D 336101, 00. html#TGO Not required to follow the Toxic Gas Ordinance (TGO) n n Not in county’s jurisdiction Designed for large quantity Silicon Valley high-tech manufacturing n Below the triggers for the TGO

SLAC ES&H Guideline (cont. ) n Devices reviewed by HEEC, guidelines provide resource for reviewers n Proposals use guideline or be able to justify deviations

SLAC ES&H Guideline (cont. ) n Engineering Controls Flow-restricting orifices to limit material released n Keep gas cylinders in a gas cabinets or well ventilated exterior location n n Small door for adjusting the regulator n Large door for changing tanks Ventilate the outside of the area surrounding the gas cylinder and laser cabinet that contains laser chamber. n Monitor ventilation with alarm n

SLAC ES&H Guideline (cont. ) n Engineering Controls n Establish location and design to protect gas systems from physical damage n Out of path of heavy equipment n Design system to survive earthquake

SLAC ES&H Guideline (cont. ) n Engineering Controls (cont. ) n Accessible gas system fittings- physical barrier to impede inadvertent loosening of fittings n Eliminate fittings entirely if possible n Due to reactivity of F 2, take extreme care in manipulation and choice of materials

SLAC ES&H Guideline (cont. ) n Administrative Procedures and Signs Post “Danger” signs n Alert Fire Department n n Provide FD Tour Turn off bottles when not in use n In event of gas system failure evacuate immediately n n Turn off cylinders and regulators only if safe to do so without protective equipment

SLAC ES&H Guideline (cont. ) n Administrative Procedures and Signs (cont. ) n n Two people minimum working on toxic gas systems Special precautions may be needed when using passivating gases n Evacuating excess staff from an effected area n Provide Safety or Security personnel to control area entry

SLAC ES&H Guideline (cont. ) n Personal Protective Equipment (PPE) for Fluorine Use n Gas proof goggles (unventilated) n Neoprene gloves

SLAC ES&H Guideline (cont. ) n First Aid n Eyewash located nearby but outside of potential exposure area n Calcium gluconate gel for use on skin- near the eyewash n Used to minimize additional damage from the HF

Equipment Design to Minimize the Hazards of F 2 Use with Eximer Lasers n Most problematic issue- Fluorine gas cylinders n Passivating gas – Higher concentration n Premix operating gas n Solution- Eliminate F 2 gas cylinders through in situ ( in-place) generation of F 2

Equipment Design Approaches (cont. ) n Generate F 2 gas in-place n Heat fluorine containing salt to generate F 2 gas n Klystron Lab Lambda Physik- In-place

Krypton Gas (inert) Lambda Physik Halo. Safe™ Unit F 2 Generator

Equipment Design Approaches (cont. ) n Some Lambda Physik Additional Safety Features n F 2 sources generate only the amount of gas needed for the laser filling cycle n F 2 is kept under negative pressure n F 2 filter eliminates the F 2 when not in use

Equipment Design Approaches (cont. ) n Advice n Buy the right equipment- In-place F 2 generation n Reports suggest that there are older generation systems available for “free” n May want to consider total costs and safety aspects of these systems

More Information n Safety Using Fluorine Eximer Lasers n n Santa Clara County Toxic Gas Ordinance n n http: //www. ehinfo. org/content/0, 4745, sid%253 D 11383%2526 chid%25 3 D 15213%2526 ccid%253 D 336101, 00. html#TGO Toxic Gas Ordinance at Stanford n n http: //www-group. slac. stanford. edu/esh/guidelines/fluorinelaser. pdf http: //www. stanford. edu/dept/EHS/prod/researchlab/tgo/ Lambda Physik- Information on Halosafe systems n http: //www. lambdaphysik. com/script/content. asp? area=products&sitep ages_id=47