Low-Vacuum Quadrupole Mass Filter Using a Drift Gas

Table 2

Experimental results obtained at 20 Pa.

No.	a value	q value	Operation point	Picoammeter current (nA)
				Traditional method (no gas flow)	Proposed method (with gas flow)
1	0	0.66	Inside the stability region	0.003	20.1
2	0.1	0.66	Inside the stability region	0.005	16.5
3	0.2	0.66	Inside the stability region	0.005	12.0
4	0.2	0.2	Outside the stability region	0.004	1.8
5	0.1	0.2	Outside the stability region	0.004	3.6