Speed limit of frozen pellets (H{sub 2}, D{sub 2}, and Ne) through single-loop and multiloop tubes and implications for fusion plasma research
Frozen pellets (H{sub 2}, D{sub 2}, and Ne at 8 K) of nominal 2.7 mm diam were shot through a coiled tube (single loop of {approx}0.6 m diam and 8.5 mm bore), and the speed limit for survival was recorded for each pellet type. Intact H{sub 2} pellets were observed at speeds approaching 500 m/s; but neon pellets could not survive much more than 100 m/s. The speed limit for D{sub 2} pellets fell in the middle at {approx}300 m/s. Some D{sub 2} pellets were also shot through a 30 m coiled tube consisting of 11 loops (average loop diameter of {approx}0.8 m), and a speed limit of {approx}100 m/s was observed. Injection of frozen H{sub 2} or D{sub 2} pellets is commonly used for core fueling of magnetically confined plasmas, and frozen neon pellets are sometimes used for impurity transport studies in similar experiments. The results from these tests add to a pellet database for injection lines with single- and complex multiple-curved guide tubes. All of the information to date suggests that frozen pellets can be delivered reliably from a pellet source to any accessible plasma location on a fusion device via ''roller-coaster'' tubes as long as the pellet speed is maintained below a threshold limit.
- Sponsoring Organization:
- (US)
- OSTI ID:
- 40204815
- Journal Information:
- Review of Scientific Instruments, Vol. 72, Issue 1; Other Information: DOI: 10.1063/1.1331322; Othernumber: RSINAK000072000001000273000001; 036101RSI; PBD: Jan 2001; ISSN 0034-6748
- Publisher:
- The American Physical Society
- Country of Publication:
- United States
- Language:
- English
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